Preheat your oven to 375°F. Line a standard 12-cup muffin tin with paper muffin liners. This takes 5 minutes and ensures easy removal and even browning.

In a large mixing bowl, whisk together 2 cups all-purpose flour, 3/4 cup granulated sugar, 2.5 teaspoons baking powder, and 1/2 teaspoon salt for 30 seconds. You are combining the dry ingredients so the baking powder distributes evenly. Checkpoint: You should see no lumps of baking powder and the mixture should look uniform and sandy.

In a separate medium bowl, whisk together 1/3 cup melted unsalted butter, 2 large eggs, 1 cup whole milk, and 1 teaspoon vanilla extract for 45 seconds until smooth and combined. Checkpoint: The mixture should be pale and homogeneous with no streaks of egg white visible.

Create a well in the center of your dry ingredients and pour the wet mixture into it. Using a spatula or wooden spoon, fold gently together 15–20 times until just combined. This takes 1–2 minutes. The batter should be lumpy and thick — do not overmix or your muffins will be dense and tough.

In a small bowl, toss 1.5 cups blackberries (fresh or thawed frozen, drained) with 1 tablespoon all-purpose flour. This coating prevents the berries from sinking to the bottom during baking. Fold the berry mixture gently into the batter with 10–12 folds over 30 seconds. Checkpoint: You should see berries distributed throughout the batter with no dry flour streaks.

Using an ice cream scoop or spoon, divide the batter evenly among the 12 muffin cups, filling each about two-thirds full. This takes 2–3 minutes. Do not overfill or batter will spill over the edges.

Sprinkle the top of each muffin with a small pinch (about 1/8 teaspoon each) of granulated sugar. This creates a subtle sweet crunch on top.

Place the muffin tin on the middle rack of your preheated 375°F oven. Bake for 18–22 minutes. At 18 minutes, begin checking: insert a toothpick into the center of a muffin (avoiding a berry). It should come out clean or with just a crumb or two. The tops should be light golden brown and spring back when lightly touched. Checkpoint: If the toothpick has wet batter, bake 2–3 more minutes and check again.

Remove the muffin tin from the oven and set it on a heat-safe surface. Let the muffins cool in the tin for exactly 5 minutes. This allows them to firm up enough to handle without breaking.

After 5 minutes, carefully tip each muffin out of its liner and transfer to a wire cooling rack. Cool for at least 15 minutes before serving. This prevents a soggy bottom and allows the crumb to set. Checkpoint: Muffins should feel just warm to the touch, not hot.