If you don’t have a nice half sheet pan, or want the thicker bars, you can definitely make them in a 9 x 13 inch pan. Simply reduce the temperature to 325 (165 degrees celsius), and bake for about 10 to 20 minutes more.

1 cup (2 sticks or 224g) unsalted butter at room temperature
2 cups (380g) granulated sugar
1 teaspoon pure vanilla extract
1 teaspoon pure almond extract
4 eggs
3 cups (300g) unbleached all-purpose flour
3/4 teaspoon salt

for the filling:
6-7 peaches, peeled and thinly sliced
1/4 cup brown sugar
1/2 teaspoon cinnamon

for the glaze:
1 cup powdered sugar
2 tablespoons cream
1 teaspoon pure vanilla extract

1. Preheat oven to 350 degrees 180 degrees celsius). Grease a large cookie sheet (half sheet) with butter or nonstick spray. In the bowl of an electric mixer fitted with the paddle attachment, cream together butter and sugar, until smooth and fluffy, about 2-3 minutes. Add in eggs, one at a time, incorporating well after each addition. Add in vanilla and almond extract. Slowly add flour and salt, and mix until just incorporated.

2. Spread three-fourths of the mixture into the prepared pan. Mix the peaches, brown sugar, and cinnamon in a medium sized bowl, and distribute evenly over the batter. Drop the rest of the batter by tablespoonfuls over the peaches, and bake for 25-30 minutes, or until the edges start to turn golden brown.

3. Whisk together the powdered sugar, water, and cream and drizzle half of the mixture over the warm bars. Allow to cool, cut into 3 inch squares, and drizzle over the remainder of the glaze.