In a slow cooker, place the chicken breasts in the bowl and sprinkle on the olive oil, onion powder, thyme and salt evenly onto the chicken. Cover the cooker and cook on high for 4 hours or until the chicken is juicy and easy to shred. Shred the chicken with two forks.
Fill a large pot with water and bring it to a boil. throw in the pappardelle noodles, making sure that they are separated in the pot. Boil according to package directions, around 6-7 minutes. Remove from the heat and strain.
To make the sauce, heat the olive oil in a medium fry pan over medium-low heat until the oil shimmers. Toss in the garlic and onion and sauté for 3-4 minutes, until the onions appear translucent and slightly brown.
Remove the pan from the heat and then add the vodka. Return to the heat and cook until the liquid is reduced by half. Add the tomatoes, red pepper flakes, and a pinch of salt and pepper. Simmer, uncovered for 10 minutes.
Add the cream and stir the sauce over medium high heat until well combined, 1-2 minutes.
Add the pappardelle and shredded chicken back into the pot. Pour in the vodka cream sauce onto the noodles and chicken and toss well. Sprinkle on the parsley and top with mascarpone cheese when serving. Enjoy hot and save leftovers in the fridge for 2-4 days.