Preheat your oven to 350°F (175°C) and generously grease an 8-hole friand pan or standard muffin tin with butter. This ensures the delicate cakes will release easily after baking.

In a small saucepan, melt the butter over medium heat until it begins to foam and turn golden brown, emitting a deeply nutty aroma. This takes about 5 to 7 minutes. Remove from heat immediately and set aside to cool slightly.

In a large mixing bowl, whisk together the almond flour, powdered sugar, gluten-free all-purpose flour, and lemon zest. Ensure the dry mixture is well combined and entirely free of lumps.

In a separate clean bowl, whisk the egg whites until they are frothy and bubbly, but not holding stiff peaks. This light aeration should take about 1 to 2 minutes of vigorous whisking by hand.

Make a well in the center of the dry ingredients, then pour in the frothy egg whites, the slightly cooled brown butter, and the lemon juice. Gently fold the mixture together using a silicone spatula until just combined, being careful not to overmix.

Divide the batter evenly among the prepared pan holes, filling each about three-quarters full. Drop 3 to 4 fresh blueberries gently onto the top of each unbaked friand.

Bake for 20 to 25 minutes, or until the friands are beautifully golden brown on top and a toothpick inserted into the center comes out clean. The edges should look slightly crispy and pull away from the pan.

Allow the friands to cool in the pan for 5 minutes before carefully transferring them to a wire rack to cool completely. Serve with a light dusting of powdered sugar alongside a hot cup of Earl Grey tea.