1-First Step: Mise en place and oven prep Preheat the oven to 375°F. Line a rimmed baking sheet with parchment paper to prevent sticking and catch any drips. Trim the crusts off the 14 very thin slices of firm white sandwich bread and set the crusts aside to make breadcrumbs later.

2-Second Step: Prepare the fillings In a medium bowl, combine the 1/2 pound (8 ounces) coarsely grated sharp white Cheddar cheese, 1/2 pound (8 ounces) chilled center-cut bacon that has been finely chopped, and the 1 small yellow onion, finely diced (about 1/2 cup). Add 2 tablespoons coarse cut bottled horseradish, 1/2 teaspoon Kosher salt, and 1/4 teaspoon freshly ground black pepper. Mix everything together until well combined so each spoonful will spread evenly on the bread. Tip: Grating the cheese fresh helps it melt smoothly because freshly grated cheese lacks added anticaking agents.

3-Third Step: Assemble the toasts Spread about 1 1/2 tablespoons of the cheese-and-bacon mixture evenly on each trimmed bread slice, spreading all the way to the edges. Work quickly so the bread does not absorb too much moisture. Arrange the assembled toasts in a single layer on the prepared parchment-lined rimmed baking sheet.

4-Fourth Step: Optional make-ahead and freezing If you want to prep ahead, layer unbaked toasts between sheets of wax paper and store them in an airtight container. They can be frozen for up to two weeks. To bake from frozen, thaw in the refrigerator first for best results; this reduces the chance of soggy bread.

5-Fifth Step: Bake for golden edges and bubbly cheese Place the baking sheet in the preheated 375°F oven and bake for 25 minutes or until the edges brown and the mixture is bubbly and golden. Oven times vary, so check at 20 minutes on your first batch. The thin bread crisp will brown and the bacon will finish cooking in the oven.

6-Final Step: Finish and serve Remove the toasts from the oven and let them rest for 1 minute. Cut each toast diagonally in half, sprinkle with 2 tablespoons minced fresh flat-leaf parsley, and serve warm. These taste best straight from the oven when cheese is melty and edges are crisp.