Preheat the oven to 350 degrees F (175 degrees C).
Very finely dice the Green Bell Pepper (1) and Onion (1/2).
Mince the Garlic (4 clove).
In a large saucepan over medium-high heat, bring around 8 cups of water and around 1 Tbsp of Salt (to taste) to a boil.
To make your topping, crush the Corn Flakes (2 cup). You don’t want to crush them completely, just break them down into smaller pieces. A plastic bag and a rolling pin work well for this.
In a small bowl, combine the crushed flakes with Olive Oil (2 tablespoon), half the minced garlic, Garlic Powder (1 teaspoon), Crushed Red Pepper Flakes (1/2 teaspoon), Parmesan Cheese (1/2 cup), and a pinch of Salt (to taste) and Ground Black Pepper (to taste). Toss to combine. Set aside.
Once boiling, add the Rotini Pasta (8 ounce) and cook until 4 minutes before directed on the packaging. You want it to still have quite a bit of chew to it.
Drain, reserve 1 cup of pasta water, and set noodles aside.
Add Vegetable Broth Paste (1 teaspoon) to the hot stock and stir to combine.
To the same pot, add a generous splash of Olive Oil (as needed) over medium-high heat. Add the onion, green pepper, and garlic and cook, stirring occasionally, for 3-5 minutes or until the onions and pepper begin to soften.
Stir in the hot pasta stock, Sour Cream (1/2 cup), Dijon Mustard (1 teaspoon), Paprika (2 teaspoon), Worcestershire Sauce (1/2 teaspoon), and a generous pinch of Salt (to taste) and Ground Black Pepper (to taste).
Turn heat to medium and add the White Cheddar Cheese (1 1/2 cup). The heat will help the liquid emulsify into a sauce. Cook for 2-3 minutes, stirring gently until the liquid thickens.
Turn off the heat. Add the Canned Tuna Packed in Water (2 can), Jarred Diced Pimentos (1 jar), and noodles and stir to combine. The sauce should be thick enough to coat the noodles.
Pour into a 9x13-inch casserole dish, then top with the garlic cornflake mix.
Bake in the oven for 20-25 minutes. You want the top to become a golden brown.
Let cool for 10 minutes to allow the casserole to set, then serve. Garnish with Fresh Parsley (to taste) if desired.