Enjoy these delicious moist muffins with bits of berry in every bite! You can use raspberries if blackberries are unavailable.
Makes 15-20 muffins
Preheat oven to 375 degrees Fahrenheit.
To make the streusel, add flour, light brown sugar, cinnamon, salt, and cubed cold butter to a bowl. Crumble the mixture together with your fingers until a “sandy” texture is formed. There should be some pea sized crumbs of streusel.
To make the buttermilk, add one tablespoon of white vinegar to a one cup measuring cup. Fill the cup the rest of the way with milk. Let it sit for five minutes- it will look curdled and add a nice tang and flavour to the muffins!
In a large mixing bowl, sift together the cornstarch and flour. Add the sugar, baking powder, and salt, and whisk to combine.
Make a well in the centre of the dry ingredients, and to the well add the buttermilk, oil, egg, and vanilla extract. Whisk lightly with a whisk to break up the egg, switch to a spatula, and gently fold the dry into the wet ingredients in the centre. Mix the batter just until combined.
Lightly spray muffin liners with nonstick spray. Fill each about a quarter full with batter, add some blackberries, and more batter on top. Top with another blackberry and a generous heaping of streusel.
Bake for 25–30 minutes (depending on your oven), until muffin tops are set.
If you are using smaller muffin containers, you can fill the cups with batter and only add blackberries to the top. With taller moulds, I like adding blackberries in the centre as well.
Per the recommendation of the OU, blackberries and raspberries must be inspected individually over a white cloth or lightbox. If insects are found, none of the berries in the container may be used.