To thaw the frozen spinach, place it in a fine mesh sieve and run cool water over it until the ice is all gone. Squeeze out all of the excess moisture in a tea towel or in fistfuls over the sink. Set aside.

In a small-to-medium skillet over medium heat, warm the olive oil until shimmering. Add the green onions, poblano pepper, red pepper flakes (if using) and ¼ teaspoon salt. Cook, stirring often, until the green onions are frazzled and lightly golden around the edges and the peppers are tender, about 8 to 10 minutes.

Add the drained spinach, cream cheese, sour cream, drained artichoke, and several twists of black pepper. While stirring constantly, cook until the ingredients are thoroughly mixed together, warmed through and lightly steaming, about 2 to 4 minutes. Season with additional salt and pepper, to taste (careful, the dip is hot!).

Serve warm with any desired accompaniments. Leftover dip will keep in the refrigerator, covered, for up to 4 days. Gently reheat in the microwave or on the stovetop before serving.