In a medium saucepan, whisk together the egg yolks, sugar, salt and cornstarch. Add in the pineapple juice and lemon juice, and whisk until everything is combined. Set your burner to medium heat and place your saucepan on the burner. Cook, whisking constantly, until the mixture comes to a boil and thickens. Reduce heat and simmer 1 minute more, stirring constantly. Remove from heat and whisk in the butter until it melts. Set aside.
Place flour, baking powder, baking soda, and salt in a medium bowl and whisk together. Set aside. In a separate large bowl, whisk together the egg, sugar, vanilla, melted butter, and buttermilk. Add the dry ingredients to the wet and mix until combined, but don't over mix. The batter should be thick.
Heat some oil in a pan and when hot, drop 1/4 cup of the batter. Cook the pancakes until bubbles form on top, about 2 to 3 minutes. Then top each pancake with a pineapple ring and place a maraschino cherry in the center of the ring. Carefully flip over and cook other side for about 2 minutes, until pancake is cooked through and is lightly browned. Serve immediately with pineapple curd. Enjoy!