Heat a large skillet over medium heat with vegetable oil. Add green bell pepper, Onion, celery, and cook for 6 min until soften. Add Cajun seasoning & garlic cook for additional 3 min then pour mixture in a large bowl.
In that same skillet add diced or sliced sausage (depends on preference) with a little oil and saute for 8min until cooked through. mix sausage in bowl with cooked vegetable and set aside.
Place skillet back on heat an add flour. With a spoon scrape skillet to release meat particles. pour in chicken stock slowly and making a roux. Cooked out flour taste approx 3min continuing to stirring in stock. Add in milk continue to stir with a whisk about 8 min. remove from heat and stir in Gouda cheese. Mix well until smooth. Add Salt & pepper if needed.
In a large pot bring to boil 4 cups of water. Add shells when water boils and cook for 10 min or until al dente. Remove shells and drain place one shell in a muffin tin to fill ( great tip for filling shells)
Fill each shell with sausage mixture about tablespoon amount. Pour on Cheese sauce and top with bread crumbs, Enjoy!