Step 1

Melt butter in a skillet over low heat. Add bread crumbs. Cook and stir until butter is incorporated into the bread crumbs. Remove from skillet and set aside.

Step 2

Place spinach in a microwave-safe baking dish. Add water. Cover and cook on high for 7 1/2 minutes, stirring halfway through. Drain over a measuring cup. Add enough evaporated milk to make 1/2 cup. Set aside.

Step 3

Melt butter in the skillet. Add flour and cook, stirring continuously, until mixture turns paste-like. Add onion and cook, stirring constantly until soft and translucent, 4 to 5 minutes. Add garlic and cook until fragrant, about 1 minute. Slowly add milk mixture, stirring constantly. Mix in cheese, Worcestershire sauce, red pepper flakes, salt, and pepper. Add spinach and cook until well incorporated, 2 to 3 minutes.

Step 4

Set an oven rack about 6 inches from the heat source and preheat the oven's broiler.

Step 5

Place spinach mixture in a small greased baking dish, top with bread crumbs, and place under the broiler until bread crumbs are golden, about 5 minutes.