Preheat the Oven or Air Fryer: Preheat the oven to 380°F (180°C) or preheat the air fryer to 340°F (180°C).

Sauté the Vegetables: In a large skillet, heat the butter or oil over medium heat.

Add the chopped onion and minced garlic, sautéing until the onion is translucent.

Add the chopped spinach to the skillet and cook until wilted. Remove from heat.

Prepare the Bread Mixture: In a large bowl, combine the cubed bread, cooked bacon, shredded cheese, and the spinach mixture.

Prepare the Egg Mixture: In another bowl, whisk together the eggs, evaporated milk, salt, garlic powder, black pepper, and mustard powder (if using).

Combine and Soak: Pour the egg mixture over the bread mixture, ensuring all pieces of bread are well coated.

Let it sit for about 10 minutes to allow the bread to soak up the liquid.

Bake: Transfer the mixture to a greased baking dish.

Bake in the oven for about 20 minutes or until the top is golden brown and the pudding is set.

If using an air fryer, bake for about 12-13 minutes or until cooked through.

Garnish and Serve: Garnish with fresh or dried herbs before serving.