Preheat the oven to 425°F (220°C). Line a muffin tin with paper liners and set aside.

Prepare the crumb topping. Melt the butter and allow it to cool slightly. In a medium bowl, combine the flour and sugar. Slowly drizzle in the melted butter while stirring with a fork until a crumbly mixture forms with small and large clumps. Set aside.

In a large bowl, whisk together the eggs and sugar until smooth and slightly pale.

Add the sour cream, vegetable oil, and vanilla extract. Mix until fully combined.

In a separate bowl, sift together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, whisking until just combined and no lumps remain. Do not overmix.

Gently fold in the raspberries, allowing a few pink streaks in the batter.

Divide the batter evenly among the prepared muffin cups, filling each about ¾ full.

Generously sprinkle the crumb topping over each muffin.

Bake at 425°F (220°C) for 5 minutes. Without opening the oven door, reduce the temperature to 350°F (180°C) and continue baking for 13 to 15 minutes, or until the tops are golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.

Allow the muffins to cool in the pan for 10 minutes before transferring them to a wire rack to cool completely.