Preheat your oven to 350°F. Grease and flour a 9-inch round cake pan.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, salt, and sugar until well combined.

In a separate bowl, use an electric mixer to cream the butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

Gradually add the dry ingredients to the wet ingredients, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.

Pour the batter into the prepared cake pan and smooth the top. Bake in the preheated oven for 45-50 minutes, or until a toothpick inserted into the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

In a bowl, gently toss the blueberries with the sugar and lemon juice. Let the mixture sit for at least 10 minutes to allow the berries to release their juices.

Once the shortcake is completely cooled, slice it horizontally. Spread half of the blueberry filling over the bottom layer, then place the top layer back on.

Top the assembled shortcake with the remaining blueberry filling and dust with powdered sugar. Serve with whipped cream or vanilla ice cream if desired.

Store any leftover shortcake in an airtight container in the refrigerator for up to 3 days. Bring to room temperature before serving.