Grease a 9-inch round or square baking pan and line the bottom with parchment paper.

Wash, pit, and slice the peaches into ¼- to ½-inch slices.

Toss the peach slices gently with lemon juice and set aside.

In a medium bowl, whisk together flour, baking powder, salt, and cinnamon.

In a large bowl, beat softened butter and sugar for 2–3 minutes, until light and creamy.

Add the eggs one at a time, mixing well after each addition.

Mix in the vanilla extract.

Add one-third of the flour mixture and mix gently.

Add half of the milk and mix until just combined.

Repeat with another third of the flour mixture, the remaining milk, and the remaining flour.

Fold about half of the sliced peaches gently into the batter.

Spread the batter evenly into the prepared baking pan.

Arrange the remaining peach slices over the top of the batter.

Combine the 2 tablespoons sugar and ½ teaspoon cinnamon, then sprinkle evenly over the peaches.

Bake for 45–55 minutes, or until the cake is golden and a toothpick inserted into the cake portion comes out with a few moist crumbs.

If the top browns too quickly, loosely cover the cake with aluminum foil during the final part of baking.

Cool the cake in the pan for about 15 minutes.

Transfer to a wire rack and allow it to cool further.

Dust with powdered sugar and serve with vanilla ice cream or whipped cream, if desired.