Sift flour and baking powder in a medium-size bowl. Whisk to combine.
In a separate medium-sized bowl, add softened butter and granulated sugar. Using the paddle attachment, mix on low speed until just combined, 20 seconds. Increase speed to medium and mix for 3 minutes until the mixture is light and creamy. Scrape down the sides as needed.
Add vanilla and mix on medium speed for 10 seconds.
Add eggs one at a time, on medium speed until creamy, 30 seconds. Scrape the bowl and repeat with the second egg.
Add milk and combine on medium speed, 15 seconds.
On low speed add flour mixture in 3 batches, mixing until just combined, 10 seconds each interval. Scrape sides as needed. Pour batter into the pan over the pineapples; it will be thick. Use a spatula to spread evenly.
Bake until cake is golden brown, springs back when touched and a toothpick inserted in the center comes out clean with a few crumbs attached, or center of the cake registers about 185-190°F (85-88°C), about 30 to 40 minutes. The bake time will depend on the size of your pan.
Allow cake to cool in the pan on a cooling rack for 45 to 60 minutes. The cake will still be slightly warm but will set as it continues to cook in the pan. Do not cool completely or the topping will stick to the bottom.
Run a knife around the edges of the cake, invert onto a serving platter, and then wait 5 minutes before lifting off the pan. Serve warm.
