Preheat your oven to 375 degrees Fahrenheit and line your muffin tin with paper liners and set aside.
To make the crumble topping combine the brown sugar, granulated sugar, cinnamon and salt in a medium bowl. Then whisk in the melted butter. Next, add in the flour and stir in until moist. Finally spread out the mixture onto parchment paper to dry until you are ready to use.
To make the muffin batter, in a large bowl combine the flour, light brown sugar, baking powder, baking soda, cinnamon and salt and set aside.
In a medium bowl, whisk together the milk, vegetable oil, vanilla, and eggs. Then combine the wet ingredients in the bowl with the dry ingredients and mix until the batter is smooth.
Fill each of the prepared muffin cups up ⅔ of the way with batter. This will make about 14-18 muffins in total.
For the last ⅓ of the muffin tin add in the prepared crumble topping and push it into the muffin batter so that it sticks to the wet batter and will bake properly.
Then bake in the oven for 15-20 minutes until a toothpick comes out clean.
Allow the muffins to cool and then serve and enjoy!