Preheat your oven to 425°F / 218°C and line a standard 12-cup muffin tin with paper liners.

Add all streusel ingredients to a small bowl. Mix with a fork or your fingers until clumps form and no dry flour remains, then place the mixture in the freezer while you prepare the batter.

Whisk together 1 1/2 cups of flour, 3/4 teaspoon of baking soda, 1 1/2 teaspoons of pumpkin pie spice, and 1/2 teaspoon of salt in a medium bowl and set aside.

Whisk 3/4 cup of granulated sugar, 1/4 cup + 2 tablespoons of brown sugar, 2 large eggs, 6 tablespoons of vegetable oil, and 1 cup of pumpkin puree together in a large bowl until smooth.

Add the dry ingredient mixture to the wet ingredients and stir with a wooden spoon until just combined, being careful not to overmix.

Divide the batter evenly among the 12 muffin liners, filling each about 3/4 full, then scatter the chilled streusel topping evenly over the tops.

Bake at 425°F / 218°C for 8 minutes, then reduce the oven temperature to 350°F / 177°C without opening the door and bake for an additional 8 to 12 minutes, or until a toothpick inserted into the center comes out clean.

Make the glaze by whisking 3/4 cup of powdered sugar with 2 to 3 teaspoons of whole milk, set aside.

Cool the muffins in the pan for 10 minutes, transfer to a wire rack, and drizzle with the glaze. Serve and enjoy!