Line a 7 or 8 inch square baking pan with parchment paper so it sticks out over the sides of the pan. This will allow you to lift the bars out once set.
Add the cashews, almonds, dates, cocoa powder, vanilla and salt to a food processor and blend into a crumbly but sticky dough. It should almost be coming together in one big clump as you blend and you should be able to press the dough between your fingers. If the dough seems too dry or crumbly, which can happen if your dates were too dry, add 1-2 tbsp warm water and process again. That should do the trick. Use your hands to firmly press the dough into the lined baking pan until smooth and even.
Mix the almond butter, cocoa powder, maple syrup and coconut oil together in a bowl until smooth and combined. It will be quite thick. Spread the fudge over the crust layer in the pan in an even layer.
Melt the chocolate in the microwave in 15-20 second increments or using a double boiler until completely smooth, then stir in the the almond butter. Spread the melted chocolate over the fudge layer in the pan using a spatula to evenly spread and smooth as best you can.
Place the entire pan in the freezer until the chocolate has hardened, about 20-30 minutes. The fridge is ok too, it will just take longer to set.
Once the bars are set, warm a sharp knife under hot water and score the bars by creating lines where you plan to cut. I'd suggest starting with 16 squares, though I like to slice the 16 squares into 32 mini bars. After scoring, slice and enjoy or store in the fridge or freezer.