Creamy Chicken and Broccoli Pasta Bake

This recipe was the one we cooked at the community Kitchens group on 12th August. It was really tasty. We usually make adjustments to our recipes to improve them but not on this one. It was good how it was. We doubled the recipe and had 16 serves. Also, I forgot to put the sour cream in, so we had it on the side, it was great. A side salad would have been a great addition to the pasta bake.
500g rotini pasta, uncooked
30 g butter
2 tbsp olive oil
2 cups broccoli florets, finely chopped
1 tbsp plain flour
1 cup chicken broth
1 cup milk
salt and pepper to taste
pinch chipotle chile powder (optional)
250 g Cheddar cheese, shredded
2 onion, finely diced
500 g ground chicken
230 g sour cream (optional)
Bring a large pot of lightly salted water to a boil. Add pasta and cook until al dente, 7 to 10 minutes. Drain, cover, and set aside until needed.
Melt butter in a saucepan over medium-high heat, and stir in 1 tablespoon olive oil. Add 1/2 the broccoli; toss and cook just until tender, about 5 minutes. Sprinkle broccoli with flour, and cook 1 minute. Stir in the chicken broth, and bring to a boil. Pour in the milk, and stir to blend. Season with salt, pepper, and chipotle pepper powder, if desired. Reduce heat to medium, and simmer mixture until sauce thickens, 8 to 10 minutes. Mix in half the cheese and stir until melted. Remove from heat.
Heat the remaining olive oil in another large skillet over medium-high heat. Stir in the onion, ground chicken, and remaining broccoli. Cook and stir until chicken is evenly browned and no longer pink, about 10 minutes. Season to taste with salt and pepper. Reduce heat, and cook until liquid is reduced, about 5 minutes.
Preheat grill to High. Lightly grease 9x13 inch baking dish.
Toss the pasta with the broccoli sauce until evenly blended. Stir in the sour cream, if desired. Stir the broccoli sauce mixture into the chicken mixture. Spoon into the prepared baking dish. Top with remaining cheese.
Cook under preheated griller until cheese melts and browns around the edges, 3 to 5 minutes. Alternatively, oven bake 10-15mins.