In a large skillet, heat 2 tablespoons of oil over medium heat. Add 1 diced onion and 3 minced garlic cloves, cooking until softened and golden, about 5-7 minutes.

Season a 3-4 pound beef chuck roast generously with salt and pepper. Once the onions are ready, add the beef to the skillet, searing each side for about 4-5 minutes until browned.

Stir in 2 tablespoons of chili powder and 1 tablespoon of brown sugar to the skillet, mixing well with the beef and vegetables for about 3 minutes.

Pour in one 28-ounce can of crushed tomatoes and one 4-ounce can of diced green chiles into the mixture. Bring this to a simmer, stirring occasionally for about 5 minutes.

Transfer the entire contents of the skillet into your slow cooker. Add 2 cups of beef broth and set the slow cooker on low for 8 hours.

After cooking, remove the beef roast from the slow cooker using tongs, shred with two forks, then return to the slow cooker.

Scoop servings of your Slow Cooker Texas Style Chili into bowls while it's hot. Top with sour cream, shredded cheese, and chopped green onions.