Preheat oven to 400°F (200°C). Line a baking sheet with parchment.

Toss baguette slices with 2 tablespoons olive oil, salt, and pepper. Arrange in a single layer and toast in the oven for 8–10 minutes until golden and crisp. Set aside.

Pat the beef tenderloin dry with paper towels. Season evenly with kosher salt, black pepper, and garlic powder.

Heat 2 tablespoons olive oil in a heavy skillet over medium-high heat until shimmering. Add the tenderloin and sear on all sides until a golden crust forms — about 2–3 minutes per side for a medium-rare finish depending on thickness.

Add 1 tablespoon butter to the pan for the last 30 seconds, spooning it over the beef. Transfer the tenderloin to a cutting board and tent loosely with foil. Let it rest for 8–10 minutes.

In the same skillet, reduce heat to medium and add 1 tablespoon butter. Sauté the minced shallot for 1–2 minutes until translucent, then add the garlic and cook 20–30 seconds.

Pour in the white wine (or chicken broth) to deglaze the pan, scraping up browned bits. Let it reduce by about half — 2–3 minutes.

Stir in the heavy cream and bring to a gentle simmer. Add the grated Parmesan in small handfuls, whisking until smooth. Season with black pepper and a pinch of nutmeg if using.

Taste and adjust salt/pepper. Keep warm on low.

Slice the rested tenderloin into very thin medallions (about 1/8–1/4 inch thick).

Place a small spoonful of parmesan cream sauce on each toasted baguette round.

Top with a slice or two of beef tenderloin.

Spoon a bit more sauce over the beef, sprinkle with chopped parsley and chives, and add an arugula leaf if desired.

Finish with a tiny drizzle of balsamic glaze for a sweet-tart lift if you like.

Arrange on a platter and serve warm. These are best eaten within an hour of assembly so the crostini stays crisp.