In a large mixing bowl, combine 2 cups flour, sugar, yeast, and salt, whisking together until evenly distributed.

Create a well in the center and pour in warmed milk, melted butter, eggs, and vanilla extract, stirring until a shaggy dough forms.

Gradually add remaining flour, one-half cup at a time, mixing until dough comes together and pulls away from bowl sides.

Turn dough onto a lightly floured surface and knead for 8-10 minutes until smooth, elastic, and slightly tacky.

Place dough in a lightly greased bowl, turning once to coat, then cover and let rise in a warm place for 1-1.5 hours until doubled.

While dough rises, combine raspberries, sugar, cornstarch, and lemon juice in a saucepan over medium heat, stirring frequently.

Cook for 5-7 minutes, mashing berries slightly, until mixture thickens to jam-like consistency. Remove from heat and cool completely.

Punch down risen dough, turn out onto floured surface, and divide into 8-10 equal portions.

Roll each portion into a 10-inch rope, flatten slightly, and spread a tablespoon of raspberry filling down the center.

Fold dough over filling lengthwise, pinch seam closed, then twist into a spiral and tuck end underneath to form round bun.

Place shaped buns on parchment-lined baking sheet, spacing 2 inches apart, cover loosely, and let rise 30-45 minutes until puffy.

Preheat oven to 375°F (190°C) during final 15 minutes of second rise.

Bake for 18-22 minutes until golden brown with filling bubbling slightly.

Transfer to wire rack, cool at least 15 minutes, then dust with powdered sugar and garnish with fresh raspberries.