Another joint birthday has come and gone. My youngest daughter, Lauren, and I both have birthdays in February, only two days apart; we have been sharing a cake ever since she was a tot. Back in the day, before Lauren became a professional chef trained by Marc Thuet, the joint cake was a Betty Crocker Devil’s Food mix with Duncan Hines French Vanilla Frosting, decorated with Smarties (M&M’s if we happened to be in the United States). It was considered the creme-de-la-creme of birthday cakes. 🙂

That all changed about a decade ago when Lauren produced this magical cake for daughter Kirsten and her husband Mike’s joint birthday celebration in March (they’re only a couple of weeks apart, so get lumped together, too!).

I’ve made it before, in parfait form, without the Peanut Butter Crackle layer you see immediately above the brownie base. The additional layer, my friends, contains a glorious mixture of peanut butter, milk chocolate, chopped peanuts, crispy Corn Flakes (or Rice Crispies – your choice), and chopped mini Reese’s Peanut Butter Cups.

The cake is quite dense; I suggest serving small portions. Happily, it slices beautifully, so thin slices are easily cut. We served 11 people with just over half the cake (leftovers gratefully taken home).

By the time we wrapped up a dinner of roast beef with Yorkshire puddings (36 of them, no less), roasted butternut squash, steamed green beans, and mashed potatoes, I had run out of energy (and light) to get a photo of the cake slices. You get the idea, though!


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Better-Than-Crack-Brownie Cake

A sublimely rich chocolate brownie base topped with layers of peanut butter crackle, peanut butter mousse and chocolate mirror, garnished with Reese’s Pieces, Peanut Butter Cups (dark and mini), and salted peanuts.



For the brownie base

  • 300 g eggs (4 large)
  • 200 g or 1 c granulated sugar
  • 180 g or 7/8 c brown sugar, packed
  • 227 g or 8 oz melted butter
  • 150 g or 1 c cocoa
  • 10 ml or 2 tsp vanilla extract
  • 60 g or ½ c unbleached, all-purpose flour
  • 3 g or ½ tsp salt

For the peanut butter crackle layer

  • 160 g or 1 c milk chocolate
  • 270 g or 1 c smooth peanut butter
  • 5 g or 1 tsp butter
  • 30 g or 1/3 c salted peanuts, chopped
  • 22 g or 1 c Corn Flakes or Rice Crispies
  • 100 g or 2/3 c mini Reese’s Peanut Butter Cups, chopped into quarters

For the peanut butter mousse

  • 250 g or 8 oz cream cheese, cut into 1″ cubes
  • 270 g or 1 c peanut butter
  • 150 g or 1 ½ c confectioners’ sugar
  • 250 g or 1 c heavy cream (35%)

For the chocolate mirror*

  • 5 g gelatin sheet
  • 100 g or ½ c granulated sugar
  • 55 g or ¼ c water
  • 33  g or 1/3 c cocoa powder
  • 30 g or 2 tbsp cream (35%)
  • 28 g or 1 oz dark chocolate (70-80%), chopped into pieces

For garnish (optional)

  • Chopped Reese’s Pieces, Peanut Butter Cups or Minis, chocolate-covered or plain, salted peanuts, and a dusting of confectioners’ sugar


Make the brownie layer

  1. Preheat the oven to 300°F Convection Bake or 325°F non-convection.
  2. Grease and line a 9″ springform pan with parchment paper. If using a good-quality baking spray, apply just before adding the batter.
  3. In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs until fluffy and pale yellow. Add both sugars and beat until fluffy. Add the remaining ingredients and mix until combined. The batter will be quite thick
  4. Spread the batter carefully into the parchment-lined pan. Bake for 45 minutes, or until a toothpick inserted in the centre comes out clean. Let cool completely in the pan.

Make the peanut butter crackle

  1. In a large bowl, microwave the milk chocolate until just melted (1-2 minutes at half power). Add the peanut butter and butter and stir until melted (you may need another minute or so in the microwave). Add the peanuts and cereal and stir to coat.
  2. Pour onto the brownie layer and sprinkle the peanut butter cup pieces. Tip the pan in each direction until the layer smooths out, and the peanut butter cup pieces are coated with filling. Let cool completely.

Make the peanut butter mousse

  1. In the bowl of a stand mixer fitted with the whisk attachment, beat the cream until it forms stiff peaks. Remove the whipped cream to another bowl.
  2. Switching to the paddle attachment, beat the cream cheese and icing sugar in the mixer bowl until just combined (1-2 minutes). Add the peanut butter and beat until combined (1-2 minutes). Fold in the whipping cream by hand.
  3. Spread the mousse on top of the peanut butter crackle layer. (You may need to add a parchment paper collar in the cake pan to contain all the mousse). Chill until firm.

Make the chocolate mirror*

  1. In a medium bowl, bloom the gelatin sheets with lots of cold water for at least 10 minutes.
  2. In a medium saucepan over medium-high heat, bring the sugar, water, cocoa powder and cream to a boil, whisking constantly.
  3. Remove from the heat, add the chocolate pieces and stir until combined.
  4. Squeeze the excess water from bloomed gelatine and add it to the pot. Stir until dissolved.
  5. Place a fine-mesh sieve over a jar or large measuring cup and pass the mixture through the sieve. Cover the jar with plastic wrap and chill in the refrigerator for at least 4 hours.
  6. Warm the mixture to pouring consistency before using it. You can heat it gently in the microwave on defrost to get it going, and then mix gently.
  7. Pour over the peanut butter mousse layer and tip the pan gently in each direction to create an even layer. Chill until set before adding the garnishes.


*The chocolate mirror needs to chill for several hours before being used. Though listed in the order in which it is used in the recipe, you might want to make it first.

You can also make parfaits, using an appropriately sized biscuit cutter to cut the brownie for the bottom of the cup or jar. Then add the layers of crackle and mousse, each about 1″ thick, chilling between each addition. Finally, pour the chocolate mirror over the top and garnish it with your choice of decoration.

  • Author: Lauren Kain