Preheat oven to 180ᵒC. grease a 20 x 20cm square cake tin. Line with baking paper. Put chocolate and butter in a medium saucepan over low heat, stir until melted and smooth. Cool slightly.
Stir sugar into chocolate mixture; add eggs, 1 at a time, beating with a wooden spoon after each addition until just combined. Stir in vanilla.
Combine flour, cocoa powder and baking powder in a small bowl. Add flour mixture to chocolate mixture. Stir until just combined. Stir through Tim Tams. Pour batter into prepared tin. Spreading evenly, sprinkle with almonds and sea salt flakes
Bake for 25- 30 minutes or until firm. Cool in tin on a wire rack. Remove from tin. Cut into service sizes pieces, and serve.