Preheat the oven to 325°F. Line an 8-inch square pan with parchment and lightly grease it.
Whisk the almond flour, cocoa powder, coconut flour, baking powder, and salt in a medium bowl.
In a large bowl, whisk the eggs and allulose for 1 minute. Add the Greek yogurt, melted butter, espresso, and vanilla extract, then whisk until smooth.
Stir the dry ingredients into the yogurt mixture. Fold in the chocolate chips and spread the batter into the pan.
Bake for 28 to 34 minutes, until the edges are set and the center has a soft cake texture. Cool completely in the pan.
Warm the chocolate chips and heavy cream together in short bursts, stirring until smooth. Stir in the powdered allulose.
Spread the ganache over the cooled cake and let it set for 20 minutes before slicing.