Adapted from The Best of America's Test Kitchen
For streusel topping:
1 1â„4 cups flour
65 grams (1â„3 cup) brown sugar
75 grams (1â„3 cup) granulated sugar
Pinch of salt
100 grams (7 Tbsp.) butter, melted
1 large egg
1 tsp. vanilla
1 cup sugar
4 Tbsp. butter, melted
1â„2 cup buttermilk (Rivyon)
2 cups flour
1 Tbsp. baking powder
1â„2 tsp salt
1 1â„2 cups frozen blueberries
Preheat oven to 190ÂºC
Line the muffin cups with 10-cm. by 10 cm. squares of baking paper so that the paper overhangs each muffin cup.
For the topping:
Weigh or measure out the dry ingredients into a bowl. Add the melted butter and mix until you get crumbs and the entire mixture is somewhat moistened. Set aside.
For the muffins:
Take out three medium bowls. In the first, whisk the egg until well beaten and light. Add the vanilla and sugar. Whisk until well combined. Add the butter and whisk until blended. Add the buttermilk and whisk some more. Set aside.
In the second bowl, weigh or measure out your flour. Remove one tablespoon of flour and place in the third bowl. Into the larger amount of flour, add the baking powder and salt. Whisk to combine. Add the flour mixture to the egg mixture mix until just combined.
Back to the third bowl: Add the frozen blueberries (straight from the freezer) into the flour and toss. Quickly mix the blueberries into the muffin batter. Scoop the batter into the lined muffin tins, top with prepared streusel and pop in the oven for 25 minutes until tops are browned and springy to touch.