Preheat the oven to 450°F. In a large mixing bowl, stir together 2 tablespoons of the olive oil, 1 tablespoon of the Everything but the Elote, 1 garlic clove, 1/2 teaspoon salt, and 1/4 teaspoon ground pepper.
Add the brussels sprouts, gnocchi, and red onion. Toss to coat. Spread the vegetables out onto a foil lined sheet pan.
Place the chicken thighs in another mixing bowl. Drizzle with the remaining olive oil remaining Everything but the Elote, and minced garlic. Toss to coat.
Arrange the chicken on the sheet pan, nestled among the vegetables. Place in the oven and roast for 15 minutes.
Remove the sheet pan from the oven and add the tomatoes. Return to the oven for 10 minutes, or until chicken is cooked through.