Start by preheating your oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick spray. Preheating ensures even baking and prevents sticking.

In a small bowl, mix flour, brown sugar and cinnamon. Add cold butter and use your fingers or a fork to mix until crumbly. Set aside. This topping will add sweet crunch.

In a medium bowl, whisk together flour, baking powder, baking soda, salt and cinnamon. Make sure the ingredients are evenly combined. This helps the cake rise and stay fluffy.

In a large bowl, beat softened butter and granulated sugar together until light and creamy. This step adds air to the batter for a soft texture.

Add eggs one at a time, mixing well after each. Stir in vanilla extract. The batter should be smooth and slightly fluffy.

Add half of the dry ingredients to the butter mixture. Mix gently, then add sour cream, and finally the remaining dry ingredients. Stir until just combined. Overmixing can make the cake dense.

Gently fold in the sliced peaches. Make sure they are evenly distributed but do not mash them. The peaches keep the cake moist and fruity.

Spread the batter evenly in the prepared baking dish. Smooth the top with a spatula. This ensures uniform baking.

Sprinkle the streusel mixture evenly over the top of the batter. Press lightly to help it stick. The topping adds sweetness and texture.

Bake for 40–45 minutes, or until a toothpick inserted comes out clean. The top should be golden brown, and the cake should feel set.

Allow the cake to cool for 10–15 minutes. This helps it set and makes slicing easier. Serve warm with coffee or tea.