Preheat the oven to 375°F (190°C). Pat the turkey breast dry, season all over with kosher salt and black pepper, then brush melted butter under the skin and over the top.
Initial Roast
Place the turkey skin-side up on a rack in a roasting pan. Roast uncovered for 30 minutes, until the skin starts to brown and juices glisten.
Make the Glaze
Combine cranberry sauce, orange juice, brown sugar, Dijon mustard, and cinnamon in a saucepan. Simmer over medium heat for 5 minutes, stirring until sugar dissolves.
Finish Roasting
Brush half the glaze onto the turkey. Continue roasting for 45 more minutes, brushing every 15 minutes, until an instant-read thermometer reads 165°F (74°C) at the thickest part.
Rest and Serve
Transfer the turkey to a cutting board, tent loosely with foil, and let rest for 15 minutes before slicing.
Notes
While massaging melted butter under the skin I found the meat stayed remarkably moist and flavorful.On my third attempt, brushing the glaze every 12 minutes created a jewel-like, candy-like sheen without burning.You can make the glaze up to 2 days ahead; store it in an airtight jar in the fridge and whisk gently before use.