Brioche Dough:

1. Proof the yeast: Pour 2 ⅛ ounces (or ¼ cup) of milk into a large microwave-safe bowl and microwave for 10-20 seconds, or until warm but not hot  (between 105-110ºF). Stir in one tablespoon of sugar. Sprinkle yeast on top and stir in. Let mixture sit until a foamy layer forms on the surface (about 15-20 minutes).
2. Warm butter and milk: While the yeast is proofing, combine cubed butter and remaining 6 ⅜ ounces (¾ cup) of milk in a second microwave-safe bowl, microwaving the mixture just until the butter melts (usually 40-50 seconds). Stir and let cool until lukewarm before moving on to step 3.
3. Combine into dough: Add lukewarm butter mixture to proofed yeast along with the egg. Mix together with a large spoon, breaking up the egg in the process. Add 17 ounces (4 cups) bread flour, remaining 3 tablespoons of sugar, and salt. Fold the dry ingredients in until a shaggy dough forms.
4. Knead: Turn dough out onto a lightly-floured surface and begin to knead. It should be very soft, but shouldn't stick to your hands or the kneading surface; if it does, add more flour a bit at a time. (I usually need to add no more than an additional 1 ⅛ ounces (¼ cup)). Knead until tender and elastic, about 10 minutes. Then, shape into a smooth ball.
5. Rise: Lightly grease a bowl about twice the size of the dough. Transfer dough to bowl, turning over once to coat the top surface with oil. Cover bowl with oiled plastic wrap and let rise at warm room temperature until doubled in size (typically around 90-105 minutes).

Cranberry Chocolate Filling:

1. Prep the filling: Combine cranberries and granulated sugar in a food processor fitted with the steel blade attachment. Pulse together until cranberries are finely chopped. Place back in the freezer to keep cold while rolling out dough. Chop chocolate for filling if you have not already done so (standard size chocolate chips don't need to be chopped).

Assembling and Baking the Chocolate Rolls:

1. Prep pan and rolling surface: Grease a standard 12-cup muffin pan with non-stick cooking spray. Lightly flour a surface for rolling; a large sheet of parchment works well.
2. Roll out dough:  Transfer dough to rolling surface and roll out to a 12" x 16" rectangle, keeping the thickness of the dough even throughout.
3. Add filling: Brush dough lightly with milk, leaving about a 1" clear border along the longer sides. Sprinkle cranberry mixture evenly on top, followed by chopped chocolate or chocolate chips.
4. Roll and slice: Starting with one of the 16" sides, roll dough up as tightly as possible, doing your best to keep the filling in place as you go. Once rolled into a log, use fingertips to seal dough at the opposite end, and roll the dough so that the seam is at the bottom. Use a sharp chef's knife or serrated knife to cut the log into twelve equal pieces.
5. Second rise: Carefully transfer individual rolls to prepared muffin pan. If any filling leaks out in the process, spoon over tops of rolls in pan. Lightly cover rolls with a piece of oiled plastic wrap and let rise until very puffy. Once the rolls are starting to rise above the top of the pan, they're ready to bake.
6. Bake: Preheat oven to 350ºF. Bake rolls in preheated oven for 20-23 minutes, just until the rolls around the outer edges of the pan are starting to turn golden. Let cool briefly before serving.