Preheat your oven to 375°F (190°C). Line a muffin tray with paper liners. This prevents sticking and helps muffins bake evenly with a nice shape.

In a bowl, mix flour, sugar, baking powder and salt. Stir well to combine evenly. This step ensures the muffins rise properly and have a soft texture.

In another bowl, whisk melted butter, milk, eggs and vanilla. Mix until smooth. This creates a rich and creamy base for the muffins.

Slowly add the wet mixture into the dry ingredients. Stir gently until just combined. Do not overmix or the muffins may become dense.

Fold in the blueberries gently. Make sure they are evenly spread. This helps every muffin have juicy fruit in each bite.

In a bowl, mix brown sugar, flour, and cinnamon. Add cold butter cubes. Rub with fingers until crumbly. This creates a sweet and crunchy topping. The same technique is what gives Ina Garten's blueberry crumb cake its irresistible bakery-style finish cold butter is the real secret to getting that sandy, clumpy texture rather than a gummy paste.

Spoon the batter into muffin liners. Fill each about three-fourths full. This allows room for rising during baking.

Sprinkle crumb topping over each muffin. Cover the surface evenly. This gives a bakery-style look and delicious crunch.

Place the tray in the oven. Bake for 20–25 minutes. The tops should be golden, and a toothpick inserted should come out clean.

Remove muffins from the oven. Let them cool for 10 minutes. Serve warm or at room temperature for best taste.