Heat the oven to 400° F.
Combine the espresso powder, brown sugar, sweet paprika, smoked paprika, salt, and pepper in a small bowl. Rub the mixture over the pork until the surface is entirely coated. Drizzle pork with 1 tablespoon of the olive oil. Set aside at room temperature for 10 minutes.
Add the remaining olive oil and butter to a large, oven-safe skillet over medium-high heat. When skillet is hot, add the pork and cook, turning as needed, until browned on all sides, about 8 minutes.
Transfer skillet to oven and roast pork until a thermometer inserted into the thickest part of the tenderloin reads 145° F, about 15 minutes. Remove from oven and let rest, covered, for 10 minutes.
To serve, slice tenderloin into rounds and drizzle with pan juices.