Blue Cheese and Caramelized-Onion Squares

Ingredients

• CRUST
• 2 cups all purpose flour
• 2 tsp baking powder
• ¾ tsp salt
• ¾ cup milk (preferably whole milk)
• ¼ cup olive oil
• 2 tbsp (1/4 stick) unsalted butter, melted
• TOPPING
• 2 tbsp (1/4 stick) unsalted butter
• 2 tbsp olive oil
• 3 large onions, halved, thinly sliced
• 1 tbsp finely chopped fresh rosemary
• 1 tsp sugar
• ½ tsp salt
• 1 ½ cups crumbled blue cheese