Creating Heavenly Summer Peach Bars is simple if you follow these steps:

1. Preheat Your Oven: Set your oven to 350°F (175°C). Grease a 9×13-inch baking pan.
2. Prepare the Peaches: In a mixing bowl, toss the diced peaches with 1 tablespoon of sugar and lemon juice. Set aside to allow the flavors to meld.
3. Mix Dry Ingredients: In another bowl, whisk together the flour, baking powder, salt, and cinnamon (if using).
4. Cream the Butter and Sugar: In a large mixing bowl, cream the softened butter with the remaining sugar until light and fluffy. This should take about 3-5 minutes.
5. Add the Egg and Vanilla: Beat in the egg and vanilla extract into the creamed mixture until well combined.
6. Combine Mixtures: Gradually add the dry ingredients to the butter mixture. Mix until just combined but do not overmix.
7. Spread the Mixture: Pour the batter into the prepared baking pan and spread it evenly across the bottom.
8. Add the Peaches: Distribute the diced peaches evenly over the batter, pressing them slightly into the mixture.
9. Bake: Place the pan in the preheated oven and bake for 30-35 minutes or until golden brown and a toothpick inserted comes out clean.
10. Cool: Remove from the oven and let the bars cool in the pan for 15-20 minutes on a wire rack.
11. Serve: Cut into squares and dust with powdered sugar if desired. Enjoy!

These straightforward steps guarantee that you will end up with delicious Heavenly Summer Peach Bars that everyone will love!