Brown Butter Blondies with Crushed Pretzels and Toffee

Ingredients

• 1 c. unsalted butter
• 1 ½ c. packed brown sugar
• ½ c. granulated sugar
• 2 large eggs
• 1 t. vanilla extract
• 2 c. all-purpose flour
• ¾ t. baking powder
• ½ t. baking soda
• ½ t. kosher salt
• 1 c. toffee bits
• ½ c. semi-sweet chocolate chips
• ½ c. white chocolate chips
• 1 c. (2 oz.) crushed mini pretzel sticks or twists
• ¼ - ½ t. flaky sea salt, such as maldon or fleur de sel
• add ins of your choice, optional*