Preheat the oven to 400F and line a muffin tin with paper liners.

Whisk the flour, sugar, baking powder, and salt in a large bowl.

In another bowl, whisk the milk, oil, and eggs, then fold into the dry ingredients until just combined.

Gently fold in the blueberries and divide the batter among the cups.

Rub the brown sugar, streusel flour, and cold butter together into crumbs and scatter over the tops.

Bake for 20 to 22 minutes until golden and a toothpick comes out clean, then cool 5 minutes.