Whisk the Cold Base: In a medium bowl, whisk together the Greek yogurt, prepared horseradish, Dijon mustard, lemon juice, salt, and pepper until completely smooth.
Boil and Save Water: Cook your barbecue brisket ravioli according to the package instructions. Right before draining them, scoop out a ½ cup of the hot, starchy pasta water and set it aside. Drain the pasta.
Combine Gently: Lower your empty pasta pot heat to the lowest setting. Turn the heat completely off if you are using a heavy pot like cast iron. Pour the cold yogurt mixture and the finely shredded cheddar cheese into the pot.
Emulsify with Pasta Water: Immediately add 2 tablespoons of your hot pasta water into the pot. Stir rapidly. The residual heat from the pot and the water will melt the cheddar cheese into the yogurt without curdling the yogurt. Add a splash more water if you want a thinner coating.
Sauce the Pasta: Toss your warm ravioli directly into the silky sauce until coated and serve immediately.
