Place sliced strawberries into a bowl with sugar and lemon juice. Stir everything gently until coated well. Let the berries rest for 15 minutes so they release sweet juices and become flavorful.

Preheat your oven to 350°F. Grease a 9x13-inch sheet cake pan lightly with butter or baking spray. This helps the cake release easily later and keeps the edges from sticking.

In a medium bowl, whisk together flour, baking powder, and salt until combined. Mixing these ingredients first helps the cake bake evenly and creates a soft texture throughout every slice.

In a large bowl, beat softened butter and granulated sugar until light and fluffy. This step adds air into the batter and gives the cake a tender homemade texture.

Add eggs one at a time while mixing slowly after each addition. Pour in vanilla extract and continue mixing until smooth. The batter should look creamy and slightly thick before adding flour.

Add the flour mixture gradually while alternating with milk. Stir gently until the batter becomes smooth with no dry spots remaining. Avoid overmixing because too much stirring can make the cake dense.

Pour the batter evenly into the prepared sheet cake pan and smooth the top gently with a spatula. Bake for 28 to 30 minutes until golden and a toothpick comes out clean.

Remove the cake from the oven and place it on a cooling rack. Let it cool completely before adding toppings because warm cake can melt the whipped cream quickly.

In a chilled bowl, beat heavy whipping cream with powdered sugar and vanilla extract until soft peaks form. The whipped cream should look fluffy and smooth without becoming grainy.

Spread whipped cream evenly over the cooled cake and spoon the juicy strawberries across the top. Slice and serve immediately for the freshest flavor and prettiest presentation possible.