• Preheat the oven to 350 degrees F. Line a muffin tin with liners.

streusel

• In a bowl, whisk together the flour, sugar and cinnamon. Add the butter and mix it into the dry ingredients, then use your hands to bring the streusel together until it resembles the texture of sand. I take pieces of it and squeeze together.

muffins

• In a large bowl, whisk together the flour, baking powder, soda and salt.
• In the bowl of your electric mixer, beat together the butter, oil and sugar until fluffy, about 5 minutes, scraping down the bowl when needed. Add the eggs one at a time and beat until combined. Add the vanilla extract. Add the yogurt and stir just until the yogurt is mixed in, being careful not to overmix.
• Add the wet ingredients to the dry ingredients in the bowl. Use a fork and stir the mixture together, just until the dry ingredients are combined. The batter will be super thick! Fold in the blueberries until they are evenly dispersed.
• fill the muffin tins with about 2 tablespoons of the batter, then sprinkle some of the streusel on top. Top the streusel with the remaining batter. Top the batter with what is left of the streusel, pressing gently so the crumbs adhere.
• Bake the muffins for 20 to 25 minutes, until the tops are set. Remove them from the oven and let cool completely before serving.