Pat the chicken dry and sprinkle all over with salt and pepper.
Add the oil to a large skillet over medium heat. Once hot, add the chicken, skin side down and cook undisturbed for 4 minutes. Then flip over and cook the other side for another 4 minutes.
Place the chicken, queso dip, and diced tomatoes in the bottom of a 6 quart slow cooker.
Set slow cooker to high for 3 hours or low for 6 hours.
Once cooking is done, remove the chicken to a plate, scraping off any of the dip that may be on top and putting it back in the pot.
Use a whisk to combine the dip and any accumulated juices until smooth. Serve the sauce overtop the chicken.