nstructions Preheat oven to 400 degrees. Grease a muffin tin or line with muffin liners. Add flour, sugar, and baking powder to a large bowl. Whisk to combine. Add oil to a 1 cup measuring cup. Add egg and enough milk (⅓ – ½ cup) to fill to 1-cup line. Add vanilla extract and whisk to combine. Add to flour mixture and stir until just combined. Then fold in blackberries.

To Make Streusel Topping: Mix together sugar, flour, butter, cinnamon with a fork until coarse crumbs form. Sprinkle over muffins before baking. Divide batter evenly into muffin cups. Sprinkle with streusel topping. Bake for 20-25 minutes, until a tester inserted into the center comes out clean. When muffins are done, cool for a few minutes in the muffin pan before removing to cool on a wire rack.