Prep the pan and oven: Heat your oven to 425°F (220°C).
Line a 12-cup muffin tin with paper liners or grease well. The high heat at the start helps create tall, domed muffins.
Mix dry ingredients: In a large bowl, whisk together 2 cups (250 g) all-purpose flour, 3/4 cup (150 g) sugar, 2 1/2 tsp baking powder, 1/4 tsp baking soda, and 1/2 tsp salt.
Prepare the blueberries: If using fresh, pat them dry. If using frozen, do not thaw.
Toss the berries with 1 tablespoon flour to help prevent sinking.
Combine wet ingredients: In a separate bowl or large measuring cup, whisk 2 large eggs, 1/2 cup (120 ml) buttermilk, 1/3 cup (80 ml) neutral oil, 1/4 cup (55 g) melted unsalted butter, and 1 1/2 tsp vanilla extract. Add 1 tsp lemon zest if using.
Make the batter: Pour the wet mixture into the dry ingredients. Stir gently with a spatula until just a few streaks of flour remain.
The batter should be thick and slightly lumpy. Do not overmix.
Fold in blueberries: Gently fold in 1 1/2 cups blueberries. Overmixing will turn the batter purple and toughen the muffins.
Fill the muffin cups: Divide the batter evenly among the 12 cups, filling each to the top. Sprinkle generously with coarse sugar for that bakery-style crunch.
Bake high, then lower: Bake at 425°F (220°C) for 5–6 minutes.
Without opening the oven, reduce the temperature to 350°F (175°C) and bake for another 14–16 minutes, until the tops are golden and a toothpick comes out clean or with a few moist crumbs.
Cool properly: Let the muffins rest in the pan for 5 minutes, then transfer to a wire rack to cool. This prevents soggy bottoms and helps set the crumb.
Serve: Enjoy warm or at room temperature. They’re fantastic plain or with a pat of butter.