Heat 2 tablespoons olive oil in a large broiler-proof skillet (12-inches or larger) over medium-high heat until shimmering. Add the artichoke hearts in a single layer. Cook, stirring occasionally, until browned in spots, about 5 minutes. Add 10 ounces baby spinach, a few handfuls at a time, and cook until just wilted, 2 to 4 minutes. Add the garlic and 1/2 teaspoon red pepper flakes and sauté until fragrant, about 30 seconds more. Remove from the heat.