Prep the pan: Heat the oven to 350°F (175°C). Line an 8-inch square pan with parchment, leaving an overhang for easy lifting. Lightly grease the sides.

Melt the fat and chocolate: In a microwave-safe bowl, melt 1/2 cup butter (or coconut oil) with 1/2 cup sugar-free chocolate in 20–30 second bursts, stirring until smooth. Let it cool for 2–3 minutes so it doesn’t scramble the eggs.

Whisk in the wet ingredients: Add 3 large eggs and 2 teaspoons vanilla to the melted mixture. Whisk until glossy. If using, stir in 1/2 teaspoon espresso powder.

Mix the dry ingredients: In a separate bowl, combine 1 1/4 cups almond flour, 1/3 cup unsweetened cocoa powder, 1 teaspoon baking powder, 1/2–3/4 cup granulated erythritol or allulose (adjust to taste), and 1/2 teaspoon fine sea salt.

Bring it together: Fold the dry mixture into the wet mixture with a spatula until just combined. The batter will be thick. Stir in 1/3 cup chocolate chips and 1/3 cup chopped nuts if using.

Pan and smooth: Spread the batter evenly in the prepared pan. Smooth the top with an offset spatula. For extra shine, sprinkle a few extra chips on top.

Bake: Bake 18–24 minutes. Start checking at 18 minutes. The edges should be set and a toothpick should come out with a few moist crumbs, not wet batter.

Cool completely: Let the brownies cool in the pan on a rack for at least 45–60 minutes. This sets the structure and improves the fudgy texture.

Slice cleanly: Lift out using the parchment and cut into 16 squares with a sharp knife. Wipe the blade between cuts for tidy edges.