Preheat your oven to 175°C (350°F) and prepare two 8-inch round cake pans by greasing them and lining with parchment paper.
In a large bowl, whisk together the flour, baking powder, and salt until evenly combined. Set aside.
Mash the ripe strawberries until smooth using a fork or blender. Measure out ½ cup of the juice and reserve the remaining mashed strawberries for decoration or other use.
In a stand mixer or using a hand whisk, beat the room-temperature butter on medium speed until creamy and pale, about 3-4 minutes. This creates a light, fluffy base.
Gradually add the powdered sugar to the butter, beating on low speed until fully incorporated and smooth, about 2 minutes. The mixture should be silky and pale pink.
Pour the mashed strawberries and strawberry juice into the buttercream. Mix on low until evenly blended, then increase to medium and beat for another 2 minutes until smooth and fragrant.
Gradually add the dry ingredients to the wet mixture, mixing on low just until combined. Scrape down the sides, then beat on medium for 30 seconds for a fluffy batter.
Divide the batter evenly between the prepared pans and smooth the tops with a spatula. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean and the edges are golden.
Remove the cakes from the oven and let them cool in the pans for 10 minutes. Then transfer to a wire rack to cool completely, about 1 hour. Wrap loosely in plastic if not assembling immediately.
Level the cake layers if needed. Spread a thin layer of buttercream between the layers, then apply a crumb coat over the entire cake. Chill for 20 minutes to set the crumb coat.
Frost the cake with a generous layer of the strawberry buttercream, smoothing with a spatula or bench scraper for a clean finish. Decorate with reserved strawberry slices or piping as desired.
Let the cake sit at room temperature for at least 30 minutes before slicing to allow the buttercream to soften slightly. Slice, serve, and enjoy the bright, natural strawberry aroma with every bite.
