Preheat your oven to 350°F. Line an 8x8-inch square baking pan with parchment paper, leaving a 2-inch overhang on each end.
Melt dark chocolate in a heatproof bowl set over a saucepan of simmering water, or melt it gently in the microwave. Stir in tahini, brown sugar, maple syrup and vanilla. Mix in eggs one at a time. Mix in almond flour. Sift in cocoa powder and baking powder and mix it in well. Mix in salt, then fold in the chocolate chips.
Bake for 22-25 minutes until slightly puffed with a shiny surface and a toothpick inserted someplace between the edge and the center comes out with a few moist crumbs. Transfer pan to a wire rack and let cool completely.