Crush the walnuts to about 1cm pieces. Place in the silicone steamer case, and microwave without the lid for 1.5 minutes. Take it out and leave to cool.
Chop the chocolate, and microwave in a heatproof dish with the butter for 1 minute to melt.
Mix the melted chocolate and butter together with a whisk. Add the sugar, egg, pancake mix and cocoa powder, and mix well.
Put half the walnuts into the batter and mix in with a spatula. Line the bottom of the steamer case with a parchment paper cut to fit.
Pour the batter into the steamer case, Level out the surface, and add the rest of the walnuts.
Cover with the lid, and microwave for another 2.5- 3 minutes. Then leave covered for 3 minutes to let it cook in residual heat.
When the brownie has cooled, turn the steamer case upside down onto the lid. Take out the brownie and peel off the paper.
Flip over on the cutting board, and cut the brownie into pieces.
When I made this with dark chocolate, it didn't taste that sweet even with 40 g of sugar.
These are baked in petit gateau molds. "For Christmas Bite-sized Brownies".
These are oven baked brownies. "Valentine's Day Petit Brownies (Bitter)".