Prep the spinach: Rinse well to remove grit. Dry completely with a salad spinner or clean towels.
Dry leaves sauté better and won’t steam.
Slice the garlic: Thin, even slices prevent burning and give gentle, sweet heat.
Heat the pan: Set a large, wide skillet or Dutch oven over medium heat. Add olive oil and warm until it shimmers.
Bloom the aromatics: Add garlic and a pinch of red pepper flakes. Cook 30–60 seconds until fragrant and just turning golden.
Don’t let it brown deeply.
Add spinach in batches: Add a large handful, toss with tongs until it begins to wilt, then add more. Keep the heat at medium to medium-high.
Season as you go: Sprinkle with kosher salt and black pepper while tossing. Taste and adjust.
Finish with brightness: When wilted but still vibrant green (1–2 minutes total), turn off the heat.
Add a squeeze of lemon juice and, if using, a pat of butter to gloss the greens.
Serve immediately: Transfer to a platter, scraping in any garlicky oil from the pan. Garnish with lemon zest if you like.