• This recipe is for 8-inch bundt pan (6-cup capacity). If you have 9-10 inch bundt pan (10-cup capacity), you can double the recipe.
• Get the butter, milk, and eggs out of the fridge 1 hour before you plan to bake to let them come to room temperature. You want the butter to be soft but not melting
• Preheat the oven to 350 F (180 C) for conventional oven. For a convection oven, lower the temperature by 20 F (15 C)
• Grease the bundt pan with butter and then coat with flour evenly all over the pan. Tap out any excess flour. Keep the pan in the fridge. This is to prevent the cake from sticking to the pan. I use a homemade cake goop. It works so well with any recipe that requires that I grease the baking pan.

Prepare the cake batter:

• Combine all-purpose flour, baking powder, and salt and set aside. In a bowl of a stand mixer fitted with a paddle attachment. Beat the butter and sugar until pale and fluffy, about 5 minutes.
  
• Add the eggs and the egg yolk, one at a time.
  
• After all eggs are in, scrape the side of the bowl and beat again until all is well-combined.
  
• Add 1/3 of the flour mixture and beat on the lowest speed
  
• Then add 1/2 of the milk, beat for a few seconds, and then another 1/3 of the flour, then the rest of the milk and end with the last 1/3 of flour.
  
• Beat until all is well-combined
  

Transfer cake batter to the pan:

• Spoon about 1/2 of the batter into the bottom of the prepared pan. Make sure it covers the bottom of the pan and go up slightly to the side. I kinda use the back of the spoon to make a "tunnel" for the jam later
  
• Then spoon the stiff pineapple jam on top of the batter. Try your best to center the filling so it won't touch the side of the pan. Use the back of the spoon to gently pat it down a bit so it kinda nestles a little bit into the batter
  
• Cover with the remaining batter. Smooth the top with spatula
  

Baking:

• Place in the middle rack of the oven and bake for 45-50 minutes. Start checking at 45 minutes. If you insert a skewer near the center, comes out clean

Cool down:

• Place the bundt pan on top of the cooling rack and let it cool down in the pan for 5 minutes
  
• You can run a spatula along the edges to help release the cake. Turn it upside down onto a cooling rack. Let it cool down completely
  

Serve:

• This cake is best served the next day where you will find the flavor has developed and it's really moist.

Storage:

• The cake can be kept covered at room temperature for 2-3 days. It also freezes really well. Once it has cooled down completely, I slice into serving size and I individually wrap each slice with a cling wrap and put them in a freezer bag, push all the air out and seal
• Simply thaw at room temperature for few hours before serving or thaw it overnight in the fridge. You can warm it up in the oven for a few seconds if you like