Preheat the oven to 425°F (220°C). Position the oven rack to the center position. Line a 12-well muffin tin with tulip-style paper liners* for a loftier rise or, if using regular paper liners, spray the top of the pan with nonstick cooking spray in case the muffins spill over.
In the bowl of a food processor, combine the flour, 3/4 cup (150 g) of the sugar, baking powder, baking soda, and salt. Pulse several times to blend.
Add the butter and process until the mixture resembles cornmeal, with no discernible chunks of butter.
In a large bowl, whisk together the buttermilk, eggs, lemon zest, vanilla, and almond extract.
Dump the contents of the food processor into the wet ingredients. Gently fold the ingredients until the batter is well blended with no clumps of dry ingredients.
Add the blueberries, straight from the freezer if using frozen, and gently fold them into the batter with just 4 or 5 gentle turns of the spatula to avoid streaking the batter with berry juice.
Divide the batter equally among the prepared muffin wells, completely filling each well.
Pour the remaining 1/4 cup (50 grams) of sugar into a small cup. Dampen your fingertips with water and work them through the sugar to make it clump slightly, like snow. Top each muffin with a generous pinch of this snowy sugar.
Bake the muffins for 10 minutes. Without opening the oven door, reduce the oven temperature to 375°F (190°C). Continue to bake until the muffins are golden and a toothpick inserted in the center of each muffin comes out clean, 18 to 20 minutes more.
Let the muffins cool in the pan for 2 minutes (no more and no less!) before carefully moving them to a wire rack to cool completely. (If using regular paper liner, you may first need to use a knife to loosen the edges of each muffin from the pan.) Let the muffins cool completely before serving.