Preheat your oven to 350°F (175°C) and grease a standard muffin tin or line it with paper liners.

In a large mixing bowl, whisk together the flour, sugar, baking powder, and cinnamon.

In a separate bowl, whisk together the milk, vegetable oil, egg, and vanilla extract until smooth.

Gently fold the wet ingredients into the dry ingredients until just combined.

Spoon the batter into your prepared muffin tin, filling each cup about two-thirds full.

In a bowl, combine the cold butter, additional flour, and sugar for the crumb topping, blending until it resembles coarse crumbs.

Sprinkle the crumb topping generously over each muffin.

Bake the muffins in the preheated oven for 20-25 minutes until golden brown and a toothpick comes out clean.

Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.