Sausage, cheddar cheese, perhaps a few token vegetables.

Adding chopped frozen spinach, Parmesan cheese, and creamy mascarpone elevates this casserole practically to dinner party fare.

English muffins stand in for the bread cubes, making for a stunning presentation.

Serving of spinach florentine breakfast casserole lifted from a casserole dish

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Heat the oil in a large skillet over medium-high heat.

Add the onion and cook, stirring occasionally, until translucent, about 5 minutes.

Add the garlic; cook, stirring often, until fragrant, about 30 seconds.

Serving of spinach florentine breakfast casserole lifted from a casserole dish

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Set aside to cool slightly, about 5 minutes.

Reserve 1/4 cup of the spinach mixture.

Stir until well combined and set aside.

Overhead shot of the finished breakfast casserole in a 9x13 baking dish

Lightly grease a 13x9-inch baking dish.

Arrange the bottom halves of the English muffins in the dish in three rows of two.

Evenly spread the spinach-mascarpone mixture over the muffins.

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Cover with the top English muffin halves.

Pour the egg mixture over the casserole, then press down on the English muffins to submerge.

Sprinkle with remaining 1/4 cup Parmesan.

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Cover the dish with foil and refrigerate for at least 1 hour or up to 12 hours.

Preheat the oven to 350F.

Let the casserole cool 10 minutes before serving.

Frozen spinach in a kitchen towel after squeezed to remove all moisture for spinach flornetine breakfast casserole recipe

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

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Spinach sauteed with onion and garlic for spinach flornetine breakfast casserole recipe

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Three-fourths of cooked spinach mixed with cheese and seasoning in a bowl for spinach flornetine breakfast casserole recipe

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Wet ingredients mixed with reserved spinach (1/4) for spinach flornetine breakfast casserole recipe

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Spinach and cheese filling added to a casserole dish for spinach flornetine breakfast casserole

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Parmesan added to casserole dish after wet ingredients were poured over the English muffins and filling for spinach flornetine breakfast casserole

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Baked spinach florentine breakfast casserole in a casserole dish

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

Serving of spinach florentine breakfast casserole on a plate, and in the surroundings, a casserole dish with more, a small bowl with crushed pepper, and glasses of orange juice

Simply Recipes / Photo by Fred Hardy / Food Styling by Jennifer Wendorf / Prop Styling by Lindsey Lower

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Serving of spinach florentine breakfast casserole lifted from a casserole dish

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