4 ounces unsweetened chocolate, coarsely chopped
¾ cup (1½ sticks) unsalted butter
⅓ cup unsweetened cocoa powder
1 tablespoon plus 1 teaspoon espresso powder
2 teaspoons vanilla extract
Nonstick vegetable oil spray
5 ounces almond paste
4 large eggs, room temperature
¾ teaspoon kosher salt
1½ cups sugar
1 cup all-purpose flour
¾ cup bittersweet chocolate wafers or chips
Preheat oven to 350°. Toast almonds on a rimmed baking sheet, tossing halfway through, until golden brown, 8–10 minutes. Let cool, then coarsely chop; set aside. Meanwhile, heat chocolate, butter, and cocoa powder in a medium heatproof bowl set over a medium saucepan of barely simmering water, stirring occasionally, until melted and smooth. Remove from heat and stir in espresso powder and vanilla. Let cool. Increase oven temperature to 375°. Lightly coat an 8x8" baking dish with nonstick spray, then line with parchment paper, leaving a 2" overhang on 2 sides. Coat parchment with nonstick spray. Roll out almond paste between 2 sheets of parchment to an 8x8" square (it will be very thin; it’s okay if there are some holes and/or jagged edges). Using an electric mixer on medium-high speed, beat eggs and salt in a large bowl until foamy, about 5 minutes. Gradually add sugar and continue to beat until very thick and foamy, 5–8 minutes more. Reduce mixer speed to low, add cooled chocolate mixture, and beat to combine. Fold in flour until no streaks remain. Spread half of batter in prepared pan; smooth top. Lay sheet of almond paste over batter. Spread remaining batter over almond paste; smooth surface. For fudgy brownies, bake until edges are slightly puffed but center is still slightly wobbly, 22–25 minutes. For cakey brownies, bake until edges are puffed but center is set, 25–30 minutes. Immediately top with chocolate wafers and let melt, then spread with an offset spatula to cover top of brownie. Top with reserved almonds and let cool. Using parchment overhang, lift brownie out of pan and transfer to a cutting board. Cut into 16 squares.