Preheat your oven to 204 °C (200 °C). Line a standard 12-cup muffin tin with paper liners or grease generously with nonstick spray.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, and fine sea salt until evenly dispersed.

In a separate medium bowl, whisk the eggs, melted butter, sour cream, whole milk, and vanilla extract until completely smooth and emulsified.

Pour the wet ingredient mixture into the dry flour bowl. Use a rubber spatula to fold just until mostly combined, leaving a few visible streaks of flour.

Set aside two tablespoons each of raspberries and white chocolate for topping. Gently fold the remaining raspberries and chocolate chunks into the thick batter with minimal turns.

Divide the batter evenly among the 12 prepared cups, filling them all the way to the rim. Press the reserved raspberries and chocolate pieces onto the tops and sprinkle with turbinado sugar.

Bake at 204 °C (200 °C) for 5 minutes, then reduce the oven temperature to 191 °C (190 °C) without opening the door. Bake for an additional 16 to 19 minutes until golden brown and a toothpick inserted into the center emerges clean.

Let the muffins rest in the pan for 5 minutes, then transfer them onto a wire rack to cool completely.