This Easy Tropical Sheet Cake Is Packed With Pineapple Flavor

Gather the ingredients. Preheat the oven to 350 F. Grease a 13 x 9 x 2-inch pan with non-stick cooking spray or softened butter. Line the bottom with parchment paper. In a medium-sized bowl, combine the oil and sugar and whisk vigorously to combine. Add the eggs, then the yolks, one at a time, whisking after each addition. Whisk in the vanilla and the sour cream and whisk a final time to combine. In a medium mixing bowl, combine the flour, baking powder and salt and whisk to combine. Add the dry ingredients to the wet in three installments, gently folding with a flexible spatula after each. Transfer the batter to the prepared pan and decoratively place the pineapple chunks on top. Place the cake in the preheated oven for about 55 minutes, rotating the cake at 30 minutes. The cake can be pulled from the oven when a tester inserted in the center comes out with only a moist crumb or two. Let the cake cool for 20 minutes or so, then invert the cake onto a cooling rack. Let cool to room temperature before frosting. To make the frosting, place the butter in the bowl of a stand mixer fitted with the paddle attachment and beat on low to medium-low until smooth, about 2 minutes. Begin slowly adding the sugar, about a cup at a time, alternating with the heavy cream, and keeping the mixer at the same low-ish speed. Continue slowly mixing in this fashion (adding sugar and cream, scraping with a flexible spatula periodically, and taking time to let the mixer run between additions), until most of the sugar and cream has been incorporated. Add the vinegar and salt and mix again. Add the remaining sugar and cream and slowly add the pineapple syrup, a couple of tablespoons at a time, mixing on medium-low (at the highest) for at least 5 to 10 minutes, if not longer. The frosting will be quite light, creamy, and fluffy when it is done. Generously frost the cake before serving.