To begin, prepare the crumb topping by gently combining flour, sugar, and cinnamon within a small bowl. Utilizing a cheese grater, grate the chilled butter into the mixture, stirring until a crumbly consistency is achieved. Refrigerate this crumble mixture until it is needed.

Preheat the oven to 400 degrees and arrange a muffin pan with 12 paper liners, setting it aside.

Combine flour, sugar, salt, and baking powder in a bowl, then proceed to add milk, oil, and egg. Thoroughly mix these ingredients until a uniform mixture is obtained. Gently incorporate the blueberries.

Fill each muffin cup about ¾ full with the prepared batter, then lightly sprinkle a portion of the chilled crumb mixture onto the surface of each muffin. It's worth noting that there might be some leftover crumb mixture, which can be repurposed by spreading it on a lined cookie sheet and baking at 350 degrees for approximately 3 minutes. Once baked, freeze it for future use as a delightful topping for fresh fruit paired with yogurt, pancakes, or ice cream.

Place the muffin pan in the preheated oven and bake until the centers of the muffins are fully set and the tops achieve a golden brown hue, typically taking around 20-25 minutes. Once done, savor the delectable outcome.