Adjust oven rack to middle position and heat oven to 375° (conventional) or 350° (convection). Whisk cornstarch, sugar, salt, and black pepper in a small bowl until combined. Transfer cornstarch mixture to a rimmed baking sheet. Pat tenderloins dry with paper towels, then roll in cornstarch mixture until evenly coated on all sides. Thoroughly pat off excess cornstarch mixture.

Heat oil in 12-inch heavy-bottomed nonstick skillet over medium-high heat until just beginning to smoke. Reduce heat to medium and place both tenderloins in skillet, leaving at least one inch in between. Cook until well-browned on all sides, 8 to 12 minutes. Transfer tenderloins to wire rack set in rimmed baking sheet.

In the meantime, stir ¹/₂ cup of the maple syrup together with the molasses, bourbon, cinnamon, cloves, and cayenne in a 2-cup liquid measure. After removing the tenderloins from the skillet, pour off any excess fat then return the skillet to medium heat. Add syrup mixture to skillet, scraping up browned bits with a wooden spoon, and cook for about two minutes; syrup should be reduced to a half-cup. Transfer 2 tablespoons of this reduced glaze back to the measuring cup and set aside. Using remaining glaze, brush each tenderloin with a tablespoon of glaze. Roast 12–20 minutes, until an instant-read thermometer inserted in thickest part of each tenderloin registers 130°. Brush each tenderloin with another tablespoon glaze and continue to roast two to four minutes longer, until thermometer registers 135°–140°. Remove tenderloins from oven and brush each with glaze remaining in skillet. Let rest, uncovered, ten minutes.

While tenderloins rest, stir remaining quarter cup of maple syrup into reserved glaze. Brush each tenderloin with one tablespoon mustard glaze. Transfer meat to cutting board and slice into quarter-inch thick pieces. Serve, passing extra mustard glaze at table.