Preheat the oven to 180 C / 325 F. Line a cake pan with parchment paper. * I used a 10.5 x 7 inch (26 x 17 cm) dish. An 9 x 9 inch (22 x 22 cm) dish/pan should work too.
Add the unsweetened chocolate. Leave a couple minutes and then stir slowly until half melted. Add the peanut butter and stir until melted and smooth. * If they won't melt, reheat the saucepan over low heat for about 10 seconds and turn off the heat. Do not overheat!
In a large bowl, mix well the egg yolks, stevia and baking soda.
Add the chocolate mixture and vanilla to the egg yolk mixture. Mix well.
Add 1/3 of the whites to the chocolate mixture and mix with a whisk. Then gently fold in the remaining whites with a rubber spatula in two additions until completely incorporated.
Pour the batter into the prepared pan. Smooth the surface.
Set a roasting pan on the oven rack. Pour boiling water into the roasting pan to come about halfway up the side of the cake pan.
Bake for 23 - 25 minutes. Let the cake sit in the oven for another 10 minutes. (* The cake will be very moist in the middle.)
Remove the cake pan from the water bath and cool to room temperature.
Heat the peanut butter until a bit melty in a double boiler or in a microwave. Place in a piping bag.
Pour and spread the ganache evenly over the top of the cooled cake.
Pipe the peanut butter in lines over the still wet ganache. Drag a skewer back and forth across the lines.
Chill until set, or dig in!
Calories 322 kcal, Protein 6.6 g, Total Fat 31.8 g, Total Carbohydrate 7.7 g, Dietary Fiber 2.9 g, Sugar 1.4 g
I always use SweetLeaf Stevia Powder for baking, so even though I provide the amount of other sweetener equivalent to Stevia in each recipe, that might end up in a different texture than mine.