It's very important the ingredients for this cake are room temperature - make sure to take out your eggs and butter a few hours before using; you can always take fridge temperature eggs and put them in warm water for 10-15 minutes for a quicker way of getting eggs to room temperature. You can also pop the milk in the microwave before adding to get it to room temp.
Preheat the oven to 350F (176C).
Add the room temp, softened butter and sugar to the bowl of a stand mixer. Beat together using the paddle attachment until the mixture is light in color and looks fluffy, about 5 minutes. Make sure to scrape down the sides and bottom of the bowl a few times while it is mixing to incorporate everything.
Mix the dry ingredients - flour, baking powder, and salt - together in a separate bowl.
Measure out the milk and combine with vanilla extract. Measure out the lemon juice separately. Zest the lemons and set aside the zest until ready to use.
Starting with the first three eggs, add one egg at a time to the mixer with the butter + sugar mixture; let each egg fully absorb until adding the next one.
Before adding the 4th egg, add in about 2 tablespoons of the flour mixture and mix until combined; this will help prevent the batter from splitting!
Add the 4th egg and mix until fully absorbed; then add another 2 tbsp of flour, and repeat the same process for the 5th and 6th eggs. If you have any splitting/curdling occurring at this stage, don't worry too much!
Add in about one third of the flour mixture and mix until just combined (at this stage, we are trying to avoid overmixing).
Add in half of the milk and mix until just combined; then add another 1/3 of the flour mixture, and again mix until just combined. Make sure to scrape the bottom of the mixing bowl as well to make sure everything is incorporated.
Add in the lemon zest and the lemon juice and mix until just combined.
Now add the last third of the flour, and mix until just combined; the batter should be smooth and not curdled or split at this stage; if it still looks split, you can add flour one tablespoon at a time until the batter comes back together!
Prepare the bundt cake pan (we used a 10 cup bundt pan) by using a vegetable oil based spray, vegetable shortening, or brushing the inside with vegetable oil. Try to avoid using butter, as it can sometimes cause more sticking.
Spoon in the batter to the bundt pan and smooth it out so it is even.
Bake the cake on the center rack for 40-50 minutes, checking whether the top is getting too dark throughout. If needed, cover with foil. A cake tester inserted in the cake should come out clean!
Remove the cake from the oven and let it cool for about 5 minutes before handling. Loosen any edges you can with a spatula carefully. Turn the cake out onto a cooling rack; if it doesn't release immediately, let it sit for about 10 minutes and remove from the pan.
Let the cake cool completely; when it is cool, prepare the glaze for the top by combining powdered sugar and lemon juice as needed to create a thick yet pourable glaze.
If you need to, you can trim the bottom of the cake for it to sit flat on your cake stand/plate.
Pour over the cake and garnish with lemon zest, candied lemon slices, or candied lemon peel! Enjoy this beautiful showstopping cake for any spring occasion!