Preparation Steps

• Position a rack in the center of the oven and preheat to 325°F. Line an 8x8-inch baking pan with parchment paper, leaving a couple of inches of overhang to lift the brownies out later.
• Place the peanut butter in a microwave-safe bowl and warm for 20–30 seconds until it loosens (it should be pourable but not hot). This makes it easier to blend into a smooth batter.
• In a medium mixing bowl whisk the eggs and maple syrup vigorously until slightly frothy and well combined, about 30 seconds. Whisk in the warmed peanut butter and vanilla until the wet mixture is glossy and uniform.
• Sift together the protein powder, cocoa powder, baking powder, salt, and cinnamon into a separate bowl to remove lumps. Add the dry mix to the wet ingredients and fold gently with a rubber spatula until just combined and no streaks remain. If the batter feels unusually thick (depending on the protein powder), stir in 1–2 tablespoons of milk.
• Scrape the batter into the prepared pan and smooth the top with an offset spatula or the back of a spoon. Tap the pan once on the counter to settle the batter and release any trapped air.
• Bake in the preheated oven for 16–20 minutes. Start checking at 16 minutes — the centers should be set but still slightly soft; a toothpick inserted near the center will come out with a few moist crumbs. Do not overbake. The brownies will continue to set as they cool.
• Let the pan cool on a wire rack for about 15 minutes, then use the parchment overhang to lift the slab from the pan. For cleaner slices and a firmer texture, chill the brownies in the refrigerator for 20–30 minutes before cutting into 12 squares.
• Store leftovers in an airtight container in the refrigerator for up to 5 days, or freeze individual squares for longer storage.