Start by preheating your oven to 325°F (160°C). Grease a springform pan and keep it aside for now.
Beat the softened butter and sugar together in a large bowl on high using a hand or stand mixer. Keep mixing for about 4 minutes, until the mixture becomes light, fluffy, and slightly pale.
Add the condensed milk, then mix for another minute or so until the texture is rich and velvety. Condensed milk keeps the cake perfectly moist.
Add each egg separately, mixing until smooth before the next.
Sift together the flour and baking powder. Gently combine the dry ingredients with the wet until smooth. You don’t need to overmix, just ensure everything is nicely blended.
Add lemon zest, juice, and vanilla for a tangy twist and cozy flavor.
Pour the batter into the prepared pan.
In the preheated oven, bake for 45–50 minutes until set and lightly golden. At 45 minutes, test with a toothpick; if clean, let it rest for 10 minutes before moving to a wire rack.
Once cooled, sprinkle with powdered sugar, slice it up, and savor every bite of this zesty, tender treat!