Set oven to 350°F (180°C) and position the rack in the center. Grease an 8-inch springform pan and line the bottom with parchment.
In a bowl, whisk flour, baking powder, and salt. Set aside.
With an electric mixer, beat egg whites and cream of tartar until soft peaks form. Slowly add 1/2 cup sugar and continue until stiff peaks form. Set aside.
In a separate bowl, beat butter with remaining sugar, egg yolks, and vanilla until light and fluffy.
Add flour mix and milk to the butter mixture, alternating between the two. Start and end with the flour. Mix until just combined.
Stir in 1/4 of the beaten egg whites to loosen the batter. Gently fold in the rest using a spatula.
Pour into the prepared pan and bake for 55 minutes or until a toothpick comes out clean. Cool in pan for 10 minutes, then transfer to a wire rack to cool fully.
Mix sliced strawberries with sugar, scraped vanilla seeds, and the pod. Let sit for 15 minutes, then discard the pod.
Whip heavy cream, sugar, and vanilla until stiff peaks form. Keep chilled until ready to use.
Cut the cooled cake in half horizontally. Spread whipped cream over the bottom half, layer with macerated strawberries, then top with the second cake layer. Cover the top with more whipped cream and decorate with fresh strawberries.