Dissolve yeast in warm milk with a pinch of sugar and let it sit 5–10 minutes until frothy.

In a large bowl, combine flour, sugar, salt, softened butter, eggs, and yeast mixture. Knead 8–10 minutes until smooth and elastic.

Place dough in a greased bowl, cover, and let rise for 1–2 hours until doubled in size.

Prepare the vanilla cream: whisk egg yolks, sugar, and cornstarch. Slowly add warm milk while whisking. Cook over medium heat until thickened. Remove from heat and stir in butter and vanilla extract. Chill to room temperature.

Punch down dough and divide into equal portions. Flatten each portion, spoon vanilla cream in the center, and seal edges to enclose the filling.

Place buns on a lined baking sheet, cover, and let rise 30–45 minutes.

Preheat oven to 350°F (175°C). Brush buns with egg wash for shine and bake 18–22 minutes until golden brown.

Let buns cool slightly. Dust with powdered sugar and serve warm or at room temperature. Optionally, serve with whipped cream.