Preheat the smoker to 250 degrees F.
Add the olive oil to large cast iron skillet over medium-high heat. Add the sausage and onion. Cook, breaking up the meat, until nicely browned and no longer pink. Mix in the garlic, chili powder and cumin. Cook another minute, then remove from the heat.
Note: If you don't have a cast iron skillet, you can use any fry pan, then transfer the cooked meat and onions to a grill safe dish or a disposable aluminum foil pan before adding the remaining ingredients.
Into the skillet with the sausage and onions, add the remaining ingredients and mix until combined.
Place the queso uncovered on the grill over indirect heat. Close the lid and smoke the queso for 2 hours, stirring about every ½ hour. If the queso gets too thick, you can thin it out with more evaporated milk.
Enjoy with tortilla chips!