4 tbsp unsalted butter, softened
½ cup sugar
½ tsp vanilla extract
1 cup all-purpose flour
½ tsp baking powder
1 large egg
½ cup sour cream
1 cup frozen or fresh blueberries
½ cup all-purpose flour
½ cup sugar
¼ tsp cinnamon
4 tbsp unsalted butter, cubed
1 Make the crumb by mixing the dry ingredients with the butter by hand until the mixture is pea-sized.
2 Keep the crumb mixture in a cool place until you are ready to use it.
3 Preheat the oven to 180C. Lightly grease muffin tins or use paper muffin cups.
4 In an electric mixer on medium-high speed with the paddle attachment, cream together the butter, sugar and vanilla.
5 Sift the remaining ingredients together in a bowl.
6 Add the egg to the butter mixture and blend until combined.
7 Add ¼ cup of the sour cream to the butter mixture, then half of the dry ingredients, mixing and repeating with the remaining sour cream and then the remaining dry ingredients until the batter is combined. Be sure to end with the dry ingredients.
8 Fold in the blueberries until evenly mixed.
9 Spoon the batter into the muffin tins, leaving room on top for the crumb mix.
10 Top each muffin with 1 tbsp of the crumb mix.
11 Bake for 25-30 minutes, until a toothpick inserted in the middle comes out clean.
12 Cool for at least 10 minutes before serving.