In a small bowl, combine the salt, chili powder, onion powder, garlic powder, and cayenne pepper.
Pat the chicken tenders dry and coat them thoroughly with the spice mixture on all sides.
Melt 2 tablespoons (half of the butter) in a large skillet over medium-high heat.
Add the chicken to the skillet in a single layer (work in batches if necessary) and sear until golden brown and cooked through, about 3-4 minutes per side. Remove chicken from the pan and set aside on a plate.
Reduce the heat to medium-low. Add the remaining 2 tablespoons of butter and the heavy cream to the skillet.
Simmer the sauce, whisking constantly to scrape up any browned bits from the bottom of the pan, until the mixture thickens and becomes silky (about 5-7 minutes).
Return the cooked chicken and any accumulated juices to the pan. Toss to coat the chicken in the sauce and heat through for 1-2 minutes.
Serve immediately over pasta, rice, or mashed potatoes.