Shells are the ideal pasta to pair with a light sauce of stock punctuated with mushrooms, peas, and bacon, as their recesses will capture the flavorful ingredients. Orecchiette or farfalle would work well, too.
Heat oil and butter in a 12″ skillet over medium-high. Add bacon and cook until crisp, 6 minutes. Using a slotted spoon, transfer bacon to paper towels to drain. Add mushrooms and onion and cook until golden, 6–8 minutes. Add stock and peas and cook until reduced by half, 10 minutes. Keep warm.
In a large pot of generously salted boiling water, cook pasta until al