Using an electric mixer or stand mixer with paddle attachment, cream the butter and sugar for 5 minutes until pale and fluffy.
1 cup (227g) unsalted butter, 1 cup (200g) granulated sugar
Add in the eggs, one at a time, mixing well in between. The mixture may be lumpy but that's ok. It will come together when you add the flour mixture.
4 large eggs
With the mixer on low, stir in half of the flour mixture. Add in the milk and mix for a few seconds to loosen up the batter, then stir in the rest of the flour until just combined.
2 Tbsp milk
Evenly divide the batter between the prepared pans. Spread and smooth out the surface.
Bake for 25 minutes or until tops are lightly browned and springs back when gently pressed. Let cool completely before assembling.
For the filling:
Meanwhile, whip the heavy cream, sugar and vanilla until medium peaks form.
1 cup (250ml) heavy cream, 2 Tbsp powdered sugar plus more for dusting, 1/2 tsp vanilla extract
Once the cakes are completely cooled, trim the domes of the cakes if needed. Spread the raspberry jam on top of one of the cakes. Then spread or pipe the whipped cream over the jam. Optional: reserve about 1/2 cup of whipped cream for the top of the cake if you want to top it with some berries.
1/3 cup good-quality raspberry jam
Layer with the second cake and dust with powdered sugar. Finish with the remaining whipped cream and some berries if desired.
Notes
Leftover cake can be covered and stored in the fridge for up to 3 days.