Heat 2 Tbsp olive oil in pan. When hot, add garlic and cook until golden. Add heavy cream and reduce heat until cream simmers. Allow cream to simmer until it is reduced by half, stirring frequently.
In separate pan, add remaining olive oil, spinach, and shrimp. Cook on medium until spinach reduces, and shrimp is almost fully cooked. It should be mostly pink and firm, but not fully. Turn off heat.
Add cheese, salt, and pepper to the cream when it has reduced. Stir in, and allow to melt completely. Next, add shrimp and spinach. Continue to simmer on low.
In large pot, cook fettuccine according to package directions.