Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a large mixing bowl, whisk together the flour, cocoa powder, granulated sugar, baking powder, and salt until well combined.
Add the softened butter, milk, eggs, and 1 teaspoon of vanilla extract to the dry ingredients. Beat with an electric mixer on medium speed for about 2 minutes, until the batter is smooth.
Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then transfer them to wire racks to cool completely.
While the cakes are cooling, prepare the whipped cream. In a large bowl, beat the heavy whipping cream with an electric mixer until soft peaks form. Gradually add the powdered sugar and 1 teaspoon of vanilla extract, continuing to beat until stiff peaks form.
Once the cakes are completely cooled, place one layer on a serving plate. Spread a layer of whipped cream over the top, followed by half of the sliced strawberries.
Place the second cake layer on top and spread the remaining whipped cream over the top. Decorate with the remaining strawberries and sprinkle with chocolate shavings if desired.
Slice and serve immediately, or refrigerate for up to 2 hours before serving for a firmer texture.