Preheat the oven to 350 degrees. Line a baking sheet with foil and spray with cooking spray.
Heat oil in a skillet over medium heat. Add the onion and peppers, and saute until softened, 5-6 minutes. Add the garlic and saute for another minute. Remove from heat and allow to cool while you proceed with the recipe.
In a large bowl, use your hands to break up the beef into smaller chunks. In another bowl, mix together the Ritz crackers, milk, eggs, salt, pepper, garlic powder, parsley, and peppers and onions. Add the cracker mixture to the meat mixture and gently combine, using a spatula or your hands to bring the mixture together.
Turn the meat mixture out onto the baking sheet and shape into an approximately 9 x 5 inch loaf. Bake for 35 minutes.
While the meatloaf cooks, make the glaze. Whisk together the ketchup, brown sugar, worcestershire, and dijon mustard.
Remove the meatloaf from then oven and pour the glaze over the top, letting it run down the sides. Return to the oven and bake another 15-25 minutes, or until the meatloaf reaches an internal temperature of at least 160 degrees. If desired, broil the meatloaf for 2-3 minutes to really set and caramelize the glaze.
Allow the meatloaf to set for 10 minutes before slicing and serving.