hi! i wanted to make brownies and realized i don't have a 9x13 pan as the recipe calls for. i was hoping someone here could help me out!

Brownies:

• 18 ounces semi-sweet chocolate chips (~3 completely full cups or 1 and 1/2 (12 ounce) bags)
• 9 tablespoons unsalted butter, cut into cubes
• 1 cup 2 tablespoons granulated white sugar
• 1/2 tablespoon pure vanilla extract
• 4 large eggs 1 large egg yolk
• 6 tablespoons dutch process cocoa powder
• 1/2 cup cornstarch
• 3/4 teaspoon fine sea salt
• 1 and 1/2 cups milk, semi-sweet, or dark chocolate chips

For the frosting:

• 1 and 1/2 cups good quality semi-sweet chocolate chips
• 1/2 cup heavy cream

also, baking at 350 for 27-33 minutes. her oven requires 29-30 mins. i assume the time will require change also? not sure.

recipe here

thank you so much!!