Melt the butter in a small, high-sided saucepan over medium heat. When the butter starts to foam up, drop the heat to low and cook until it reaches 300 degrees F. Fry the parsley, rosemary and sage until bright green and crisp, about 60 seconds. (Be careful: when you add the herbs, there will be splattering.) Strain the butter through a fine-mesh sieve into a heat-safe container and transfer the herbs to a paper towel-lined plate. When cool enough to handle, roughly chop.
Carefully remove the skin from the turkey breast and lay flat on a piece of parchment paper set inside a sheet pan. Cover with plastic wrap and refrigerate.
Debone the breast, remove the tenderloins and place the breast smooth-side down. Make a shallow diagonal cut in the thickest part of each lobe to open them up and then score the breast.
Cover a half sheet pan with plastic wrap, allowing 8 inches of overhang in both directions. Sprinkle the center with 2 teaspoons of kosher salt and 1 teaspoon of maple sugar and place the two breasts, flush together, directly in the center. Cover with plastic wrap and lightly pound to an even thickness. Remove the plastic wrap, realign the breasts if they've separated and brush the scored side with 3 tablespoons of the herb butter. Massage in the chopped herbs and season with 2 teaspoons of kosher salt and 1 tablespoon of maple sugar. Roll the breast into a cylinder and wrap tightly with the plastic wrap. Refrigerate overnight.
Place a rack in the center of the oven and heat to 450 degrees F.
Remove the plastic from both the skin and the roll. Carefully position the roll on the bottom of the skin. Roll up as tightly as possible, tucking the skin's edges in as you go: we're looking for full coverage here. With the seam-side down, truss the roll with twine at 1-to-2-inch intervals.
Place the roll on a rack set inside a half sheet pan, brush with 2 tablespoons of the herb butter and season with the remaining teaspoon of salt. Insert a remote probe thermometer into the center of the roll at a 45-degree angle.
Roast the turkey until the thermometer reads 100 degrees F, about 40 minutes, then baste with an additional 2 tablespoons of herb butter and rotate the pan 180 degrees. Continue to roast until the thermometer hits 150 degrees F, about 20 minutes more. Rest 20 minutes before slicing and serving.