In a bowl, whisk the flour, baking powder, and salt together until well combined. Set aside.
In a separate bowl, beat the butter on high speed in a large bowl until smooth and creamy. Add the granulated sugar and beat on high speed for 2 minutes until pale and well combined.
With the mixer running at low speed, add the eggs one at a time. Once the last egg is completely mixed in, add the sour cream, calamansi juice, lemon zest, and vanilla extract then beat on medium speed until combined.
Carefully and slowly fold the dry ingredients into the wet ingredients until just combined and there are no more dry pockets of flour. Avoid over-mixing.
Transfer and spread the batter into a prepared Bundt pan and bake in an oven preheated to177°C for 45-60 minutes. Halfway through baking, cover the top of the cake with a foil tent to prevent the top from over-browning. After baking, let the cake cool.
Sift the confectioner’s sugar into a bowl and add the milk and calamansi juice then mix until smooth and well combined.
Drizzle the calamansi icing on top of the Bundt cake and let set before slicing.
Serving Size 1 cake