How to Make It
Preheat the oven to 350°. Line a 9-inch-square baking pan with foil, allowing 2 inches of overhang on two sides. Butter the foil.
In a large bowl, using a hand mixer at low speed, mix the flour, granulated sugar, baking powder and salt. Add the 1 1/2 sticks of butter, milk, eggs and vanilla and beat at medium speed until smooth, 1 to 2 minutes. Spread the batter in the pan and bake for about 45 minutes, until a toothpick inserted in the cake comes out clean. Let cool on a rack, then cover with foil and let stand at room temperature overnight.
In a large bowl, using a hand mixer,beat the cream with the confectioners’ sugar at high speed until firm, 1 to 2 minutes. Unmold the cake; peel off the foil. Spread the raspberry jam over the cake and top with the whipped cream. Garnish with raspberries and serve.