Combine the eggs and sugar in the bowl of a stand mixer and whip on high until almost white and fluffy (about 5 minutes).
Fold in the remaining ingredients (flour, baking powder and vanilla extract) until just combined.
Pour the batter into a parchment paper lined, 8" spring-form cake pan and bake at 325F for 30-35 minute.
In a large bowl, whip your whipped cream and vanilla extract until stiff peaks form (3-5 minutes).
Remove the cake from the pan and cut in half.
Spread a thick layer of jam on top of one of your cake halves until it's about ½" from the edge.
Spoon about ⅓ of your whipped cream onto the top of the jam and spread out evenly to the edge of the cake.
Top with your second layer of cake and use the rest of your whipped cream to cover the top and sides of your cake.
Roll the marzipan out to about ¼" thick on a powder sugar or cornstarch-dusted surface.
Wrap the marzipan around your rolling pin and gently drape it over your cake.
Gently pulling away with one hand and smooth down the sides with the other, work the marzipan down to the bottom of the cake. Cut away any excess.
Decorate with marzipan flowers or fresh fruit.
