In the bowl of a stand mixer fitted with paddle attachment, beat butter and sugar at low speed until combined, 1 to 2 minutes.

Beat in egg yolk and vanilla.

In a small bowl, whisk together flour, baking powder and salt.

Add flour mixture to butter mixture, and beat at low speed then add in freeze-dried strawberry powder.

Beat until combined and a dough starts to form.

Turn out dough, and knead dough together. Shape dough into a 14-inch log, and wrap in plastic wrap. Refrigerate log until firm, about 30 minutes

In a small bowl, stir together ½ cup (120 grams) warm water, warm milk, 1 tablespoon (12 grams) sugar, and yeast.

Let stand until foamy, 5 to 10 minutes.

In the bowl of a stand mixer, whisk together 4 cups (500 grams) flour, salt, and remaining 7 tablespoons (88 grams) sugar.

Add warm milk mixture, melted butter, eggs, and vanilla extract.

Using the dough hook attachment, beat at low speed until dough comes together, 1½ to 2 minutes.

Increase mixer speed to medium-low, and beat until dough becomes tacky, smooth, and elastic, 7 to 8 minutes; add up to remaining ¼ cup (31 grams) flour, 1 tablespoon (8 grams) at a time, if dough is too sticky. (Check dough using the windowpane test [see Note] between additions of flour. Too much flour will make it harder to shape and create a denser final crumb).

Turn out onto a lightly floured surface, and shape into a smooth round Lightly oil a large bowl.

Place dough in bowl, turning to grease top. Cover and let rise in a warm, draft-free place (75°F/24°C) until doubled in size, 45 minutes to 1 hour.

Line 2 baking sheets with parchment paper. Set aside.

Punch down dough, and let stand for 10 to 15 minutes.

On a lightly floured surface, divide dough into 14 portions (about 72 grams each), and roll into smooth balls.

Flatten each ball into a 3-inch round, and place on prepared pans.

Slice Topping log into 14 (1-inch) portions.

Roll into smooth balls.

Place each ball between 2 sheets of parchment paper or plastic wrap, and roll into a 3½-inch circle. (Alternatively, roll out topping logs between 2 sheets of parchment paper. Using a 3½-inch round cutter, cut dough, rerolling scraps as necessary.)

Place on top of rolls. Using a small sharp paring knife, carefully cut desired design into Topping, leaving a ¼-inch border around edges.

Let rise in a warm, draft-free place (75°F/24°C) until puffed, about 30 minutes.

Position oven rack in top third of oven. Preheat oven to 350°F (180°C).

Bake until topping is just beginning to brown and an instant-read thermometer inserted in center registers at least 190°F (88°C), about 12 minutes.

Serve warm or at room temperature. Store in an airtight container for up to 2 days