• Preheat oven 400 F

Mushroom & Onion Filling

• Add butter to a large pot and melt over medium-high heat. Add onion and mushrooms to large pot cook out liquid, about 10-15 minutes. Drain excess liquid.
• Stir in salt, pepper, thyme, and white wine then reduce the liquid for 10 minutes, stirring occasionally. Stir in garlic and cook for 2-3 minutes or until fragrant. Remove from heat and stir in 1/2 cup of shredded cheese. Set aside to cool off.

Prepare Galette

• Flour your surface. Lightly roll out puff pastry to fit the size of your pan. Transfer puff pastry to the pan before building the galette.
• Spread boursin herb cheese spread around the center of puff pastry. Top the cheese spread with the mushroom and onion mixture.
• Securely, fold up excess sides of puff pastry around the mushroom mixture. Sprinkle the top with the remaining 1/2 cup of shredded cheese.
• Brush exposed pastry crust with egg wash. Add galette to oven to bake for 40 min or until galette crust is golden and crispy. Transfer galette to abaking rack and let cool for 10 minutes before garnishing and serving.

Balsamic Reduction

• While galette is baking, prepare the balsamic reduction
• To a small skillet over medium-high heat add balsamic vinegar and sugar and boil. Reduce liquid by half to a thick syrup, approximately 10 minutes, stirring occasionally.
• Remove from heat to cook and thicken.

Garnish

• In a bowl toss arugula and olive oil. Top the galette with arugula and drizzle with the balsamic reduction. across teh top