Grease two 8-inch (20cm) round cake tins with butter. Line with parchment paper and set aside. Preheat the oven to 375°F (190°C).
Add the butter and sugar to a large mixing bowl (or the bowl of your standing mixer). Use electric beaters to mix until very light and fluffy, 3-4 minutes.
Add the eggs one at a time, beating between each addition, until all four have been incorporated into the cake batter.
Add half the flour (¾ cup or 112 grams), the baking powder, and salt to the bowl. Mix until just combined. Add the milk and remaining flour and mix again, being careful not to over-mix.
Divide the batter between the two prepared cake tins, gently tapping to level.
Bake the cakes on the middle rack of the preheated oven for 20-25 minutes, or until the top of the cake springs back when lightly touched.
Cool the cakes for 10 minutes before removing from the tins and cooling fully on a wire rack.
To assemble, spread jam over the top of one of the cakes, followed by Chantilly or whipped cream. Top with the second cake, then dust with icing sugar.