Traditional Cinnamon Streusel Muffins

Step 1 -Preheat the oven to 350 degrees F.

Step 2 -Cut the butter into small chunks.

Step 3 -In a bowl, add 2/3 cup of the flour, 1/4 cup of the granulated sugar, 2 tablespoons of the brown sugar, the salt, and 1/2 teaspoon of the cinnamon and whisk to combine.

Step 4 -Add the butter chunks to the flour mixture and mix with a wooden spoon or a spatula just until the dry ingredients get coated with the butter.

Step 5 -Using your clean fingers, press the mixture into sand-like crumbs, with some larger ones remaining.

Step 6 -Place the streusel in the refrigerator to chill.

Step 7 -In a bowl, add the vegetable oil, 1/4 cup of the granulated sugar, and the remaining brown sugar and, using an electric hand mixer, whip together until pale and fluffy.

Step 8 -Add the egg and whip until just combined.

Step 9 -Into a bowl, sift the remaining flour, the remaining 1/4 teaspoon of the salt, and the baking powder together.

Step 10 -Add the dry ingredients mixture into the oil mixture and fold to combine.

Step 11 -In a small bowl, add the vinegar and the baking soda and mix to combine.

Step 12 -Immediately fold the bubbly vinegar mixture into the batter.

Step 13 -Spoon or pipe 1/2 of the batter into six cavities of a cupcake pan.

Step 14 -In a bowl, add the remaining cinnamon and the remaining granulated sugar and mix to combine.

Step 15 -Spoon the cinnamon-sugar over the batter in the cupcake tins evenly.

Step 16 -Spoon or pipe the remaining batter over the top of the cinnamon sugar layer in the cupcake tins.

Step 17 -Evenly and generously sprinkle the streusel mixture over the top of the muffin batter.

Step 18 -Bake until a wooden skewer inserted into the center of the muffins comes out clean, about 25 minutes.

Step 19 -Allow the muffins to cool on a cooling rack.

Step 20 -Serve.