Step 1

Cook garlic, 2 anchovies, and ⅓ cup oil in a medium Dutch oven or other heavy pot over medium heat, stirring and smashing anchovies with a wooden spoon, until garlic starts to brown around the edges, about 3 minutes. Add olives, tomato paste, capers, ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, and ¼ tsp. red pepper flakes and cook, stirring, until tomato paste turns a shade darker, about 3 minutes.

Step 2

Add 4 cups water to pot, increase temperature to high, and bring to a boil. Add pasta and spinach, tearing leaves into smaller pieces as you go. Stir to combine, then reduce heat to medium and simmer, stirring often to keep pasta from sticking, until cooked through, 10–12 minutes.

Step 3

Meanwhile, heat remaining 2 anchovies and 2 Tbsp. oil in a medium skillet over medium. Add panko and a pinch of red pepper flakes and salt and cook, stirring often and breaking anchovies apart, until golden brown, about 2 minutes.

Step 4

Divide pasta among bowls and top with panko mixture.