Heat oven to 180C/fan 160C/gas 4. Line
a 25cm square cake tin with non-stick baking parchment. Put the chocolate and butter in a microwave-proof bowl, cover and cook on High for 30 secs. Stir, continue to cook for 30 secs until the chocolate has nearly melted. When cool, but still melted, stir in half the sugar and the egg yolks.
Whisk the whites to firm peaks, add the remaining sugar, then whisk again until glossy. Stir 1 tbsp into the chocolate along with the ground almonds and breadcrumbs, then fold through the rest of the chocolate. Transfer to the tin, top with pecans. Bake for 25-30 mins. Cool in the tin for 10 mins, then lift onto a wire rack to cool completely. Cut into squares to serve.