New cheesy chicken casserole I'm trying out. I'm an aspiring home cook (never taken a culinary class or anything), and this is one of my first concoctions, but be brutally honest. Some measures are estimates, as I like to fly by the seat of my pants; Really keeps you on your toes.

2 c rotini
2 c chicken, cut into bite sizes
clove of garlic, minced
1/4-1/2 cup diced onion
1 c diced mushrooms
olive oil
around 1.5 c heavy cream
around 1.5 c shredded cheddar cheese
tsp paprika
tsp of thyme ****thinking of taking this out
1/2 tsp salt
tsp dried bay leaves
2 tsp rosemary
1 chicken bullion cube
a bit more cheddar

Preheat oven to 400, have a greased dish
Cook rotini until bit under al dente, strain
Cook chicken in a bit of oil until golden
Saute garlic, onions, mushrooms in a bit of oil, just until garlic is good, and onions are clear. Then add cream, cheese, and seasonings/herbs. Heat and stir until cheese is melted and bullion is completely stirred in. Combine chicken, rotini, and sauce in the dish, and sprinkle cheese on top.
Cook in oven 15-30 minutes.

I've made this a few times, and I think it's fairly tasty, but it feels a bit off. After making it tonight, I decided to ask some people who know what they're doing.
Any tips and advice on how to improve on this? Should I leave in the thyme or take it out? Are the proportions right? Is the cook time and temp right, etc?

Thanks, Phil