Heat oil and 2 TBsp butter in. large skillet over medium heat until butter is foaming.

Add garlic and 1/4 tsp red pepper flakes; cook, stirring often, until fragrant, about 1 minute.

Add panko and cook, stirring often, until panko is golden brown, about 2 minutes.

Mix in lemon zest and transfer panko to a paper towel-lined plate; season with salt and pepper.

Let cool; set aside. Wipe out skillet.

Cook pasta in a large pit of boiling water, stirring occasionally, until al dente. Drain.

As your pasta cooks, heat remaining 6 TBsp butter in the same skillet previously used over medium heat.

Cook, swirling skillet occasionally, until butter is brown, about 3 minutes.

Add 1 bunch of spinach; cook, tossing, until wilted (about 1 minute).

Add pasta to skillet and toss to coat.

Ad lemon juice, preserved lemon peel, and remaining 1/4 tsp crushed red pepper flakes and toss to combine; season with salt and pepper and more lemon peel and lemon juice, if desired.

Add cheese and mix into ingredients.

Add remaining spinach and toss until slightly wilted, about 1 minute.

Add and mix in the reserved panko and serve.