In a stock pot, boil the shell pasta for 8-9 minutes. Drain and set aside.
Preheat oven to 350℉.
Heat a large cast iron skillet over medium.
Cook the ground beef until cooked through and no longer pink.
Drain the grease from the ground beef on a paper towel lined plate.
Add the butter to the hot skillet.
Once the butter is melted, add the onions, garlic, and green peppers.
Saute the vegetables for 5 minutes or until tender.
Return the beef to the skillet and stir.
Deglaze the skillet with the pinot noir, scraping the bottom of the skillet to remove any brown bits. Simmer for 3-4 minutes or until the liquid has mostly absorbed.
Add the tomato paste and Worcestershire sauce and stir to combine.
Turn off the stove for the time being.
Place the pasta shells into a 13x9 baking dish.
Fill each shell with the ground beef mixture until all the shells are filled.
Pour beef broth, milk, and tapioca flour into the empty skillet.
Turn the stove burner back on to medium heat.
Whisk continuously until the mixture thickens (about 5 minutes).
After the sauce has thickened, turn the heat off and slowly add the cheddar cheese, stirring continuously to create a cheese sauce.
Pour the cheese sauce over all of the stuffed shells.
Bake, uncovered, for 15-20 minutes or until the cheese is hot and bubbly.
Remove from the oven and allow to cool for about 5 minutes before serving.