Remove any silver skin from the pork tenderloin. Slice into 1-inch medallions and gently flatten each piece to about ¾ inch thick with the heel of your hand or using a meat mallet.
In a shallow bowl, whisk salt, pepper,garlic powder and onion powder into the flour. Lightly dust both sides of each pork medallion with the seasoned flour.
Heat the olive oil and 1 tablespoon butter in a large skillet over medium-high heat.
Add the pork medallions in a single layer. Cook for 2 to 3 minutes per side until golden brown and the internal temperature reaches 145°F (63°C). Transfer to a plate and tent loosely with foil to keep warm.
Reduce the heat to medium. If the skillet contains excessive fat, spoon off all but about 1 tablespoon. Add the remaining tablespoon of butter, followed by the shallot or onion. Season with salt. Cook for 2 to 3 minutes until softened. Add the garlic and cook for 30 seconds.
Pour in the white wine and scrape up any browned bits from the bottom of the pan. Simmer until the wine has reduced by about half.
Add the chicken broth, Dijon mustard, and thyme. Simmer for 2 to 3 minutes.
Stir in the heavy cream and cook over low heat, allowing the sauce to gently simmer until slightly thickened, about 3 to 5 minutes. Avoid boiling vigorously.
Return the pork and any accumulated juices back to the skillet. Simmer gently for 1 to 2 minutes to warm through.
Stir in 1 Tbsp parsley, taste, and adjust seasoning with salt and pepper as needed. Serve with a sprinkle of parsley along with your favorite side dishes.