Instructions:
- Activate Yeast: Combine warm milk, a pinch of sugar, and yeast. Let stand until foamy (about 5-10 minutes).
- Mix Dry Ingredients: In the mixer bowl, combine flour, remaining sugar, and salt.
- Combine Wet & Dry: Add the yeast mixture, eggs, yolk, and vanilla to the flour mixture. Mix on low speed until a shaggy dough forms.
- Knead & Enrich: Increase speed to medium-low and knead for 5 minutes. Add the softened butter, one cube at a time, ensuring each piece is incorporated before adding the next. Continue kneading until the dough is smooth and elastic (about 8–10 minutes total).
- First Proof: Place dough in an oiled bowl, cover, and let rise in a warm spot until doubled in size (approx. 1.5 hours).
- Make the Streusel Base: In a separate bowl, use your fingertips or a pastry blender to cut the cold butter and shortening into the flour and powdered sugar until the mixture resembles coarse sand.
- Divide & Flavor Toppings: Divide the mixture in half. Leave one half plain (or flavour with vanilla). Mix the cocoa powder thoroughly into the second half. Chill both toppings well (at least 30 minutes).
- Divide Dough: Gently punch down the risen dough. Divide into 12 equal pieces (about 70g each).
- Shape Rolls: Roll each piece into a tight ball and place them on parchment-lined baking sheets, ensuring there is space between them.
- Second Proof: Cover lightly and let rest for 30-45 minutes until puffy.
- Apply Topping: Roll out the chilled streusel mixture (vanilla and chocolate separately) to about ¼ inch thick. Cut out 12 discs slightly larger than the dough balls. Gently place one streusel disc on top of each proofed dough ball, pressing lightly only around the edges. Score a light cross-hatch pattern onto the streusel.
- Final Proof: Cover loosely and let rest for a final 30 minutes.
- Bake: Preheat oven to 350°F (175°C). Bake for 18–22 minutes, or until the rolls are golden brown underneath and the topping is set.
- Cool: Cool on a wire rack. Best enjoyed slightly warm!