1-Preheat oven to 400F degrees and line: Preheat oven to 400F degrees and line standard muffin pan with paper liners and set aside.
2-To make the crumb topping in a: To make the crumb topping in a small bowl, whisk together flour and sugar, add melted butter and stir with a fork until crumbly and set aside.
3-To make the muffins in a large: To make the muffins in a large bowl stir together flour, baking powder and salt and set aside.
4-In a medium bowl, mix together egg: In a medium bowl, mix together egg and granulated sugar until combined. Mix in yogurt, oil, and vanilla extract.
5-Fold wet ingredients into dry ingredients and: Fold wet ingredients into dry ingredients and mix everything together by hand.
6-Spoon batter into prepared muffin tin (2: Spoon batter into prepared muffin tin (2 tablespoon in each cup).
7-Cover the batter with the raspberries and: Cover the batter with the raspberries and then cover the raspberries with streusel topping.
8-Place them in the oven and reduce: Place them in the oven and reduce the heat to 375F, bake about 18-20 minutes or until the toothpick inserted in the center comes out clean.
9-Cool for 5 minutes in the pan: Cool for 5 minutes in the pan then remove muffins and on a wire rack to cool completely.