Plugrà - Buttered Apple Baked French Toast

Ingredients

• 6 tbsp Plugrà salted butter, divided, plus more for dish
• 10 oz soft french bread or brioche, cut into 1 inch cubes (about 8 cups)
• 2 medium apples (14 ounces), peeled and sliced
• 6 tbsp granulated sugar, divided
• 1 tsp cinnamon, divided
• 5 large eggs
• 2 cups whole milk
• 1 tsp vanilla extract
• ½ tsp salt