Combine 4 cups bread flour, 1/2 cup granulated sugar, 1 packet instant yeast, and 1 teaspoon kosher salt in a stand mixer. In a separate bowl, whisk together 1 cup warmed whole milk, 1 large egg, 1 egg yolk, and 1/4 cup melted unsalted butter. Gradually mix wet into dry and knead for 10 minutes until smooth. Cover and refrigerate overnight.

Heat 2 cups whole milk with 1/2 cup sugar until steaming. Whisk together 2 egg yolks and 2 tablespoons cornstarch. Temper egg mixture with hot milk, then return to the pan and cook until thick, about 3-5 minutes. Remove from heat and mix in 2 tablespoons butter, 1/2 cup passion fruit puree, and 1 teaspoon vanilla extract. Strain, cover, and refrigerate overnight.

Transfer refrigerated dough to a floured surface and roll to 1/2 inch thickness. Use a 3-inch round cutter to punch out circles. Place on a parchment-lined tray, cover with a towel, and let rise for about 1 hour.

Heat vegetable oil to 365°F. Fry a few dough rounds for about 2 minutes on each side until golden brown. Use a slotted spoon to transfer to a paper towel-lined plate.

Once cooled, fill a piping bag with passion fruit pastry cream and gently fill each malasada until you feel resistance. Dust with sugar and serve warm or at room temperature.