Preheat your oven to 375°F (190°C).

Arrange the baguette slices in a single layer on a baking sheet.

Brush each slice lightly with olive oil on both sides.

Place the baking sheet in the oven and toast for about 8-10 minutes, flipping halfway through, until the bread is golden and crispy.

Pro tip: Keep an eye on the bread during the last few minutes so it doesn’t burn—every oven is a little different!

While the bread is toasting, heat a skillet over medium heat.

Add the chopped bacon and cook, stirring occasionally, until it’s crispy and browned, about 6-8 minutes.

Use a slotted spoon to remove the bacon and place it on a paper towel-lined plate to drain excess fat.

Carefully drain most of the bacon fat from the skillet, leaving about 1 tablespoon to cook the mushrooms.

Add the butter and minced garlic to the skillet and sauté for about 30 seconds until fragrant.

Add the sliced mushrooms and cook, stirring frequently, until they release their moisture and become tender and slightly browned—about 6-7 minutes.

Season with salt and pepper to taste.

Return the cooked bacon to the skillet and mix it with the mushrooms until everything is evenly combined and heated through.

Remove from heat and stir in the chopped parsley if using.

Spoon a generous amount of the bacon mushroom mixture onto each toasted baguette slice.

Sprinkle with grated Parmesan cheese if desired.

Serve immediately while the crostini are still warm and crispy.