Pat the pork tenderloin dry with paper towels and season generously with salt and pepper on all sides.

In a large skillet over medium-high heat, add the olive oil and butter. Once shimmering, sear the pork tenderloin for 3-4 minutes per side, until a golden-brown crust forms. Remove the pork from the skillet and set aside.

Reduce heat to medium. Add the minced shallot to the skillet and cook for 2-3 minutes until softened. Stir in the minced garlic and cook for another 30-60 seconds until fragrant.

Pour in the chicken broth to deglaze the pan, scraping up any browned bits from the bottom. Whisk in the heavy cream and Dijon mustard until smooth. Bring to a simmer and cook for 4-5 minutes, allowing the sauce to thicken slightly.

Return the pork tenderloin and any accumulated juices to the skillet. Reduce the heat to low, cover, and simmer for 10-15 minutes, or until an instant-read thermometer inserted into the thickest part reads 145°F (63°C).

Transfer the pork to a cutting board and let it rest for 5-10 minutes. Slice the pork against the grain. Serve immediately, topped with the creamy dijon sauce and a garnish of fresh parsley.