Step 1: Activate the Yeast: In a large bowl, combine the warm milk and 1 teaspoon of granulated sugar. Sprinkle the active dry yeast over the top and let it sit for 5-10 minutes until foamy. This confirms your yeast is active and ready to make fluffy banana cream crunch donuts.
Step 2: Prepare the Dough: To the yeast mixture, add the remaining ¼ cup granulated sugar, beaten egg, melted butter, and vanilla extract. Whisk to combine. Gradually add the all-purpose flour and salt, mixing with a wooden spoon or stand mixer with a dough hook until a shaggy dough forms. Continue to mix/knead for 5-7 minutes until the dough is smooth and elastic. It should be slightly tacky but not sticky.
Step 3: First Rise: Lightly grease a clean bowl. Place the dough in the bowl, turning once to coat. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm place for 1-1.5 hours, or until doubled in size. This crucial step ensures light and airy banana cream crunch donuts.
Step 4: Shape the Donuts: Once risen, gently punch down the dough. Turn it out onto a lightly floured surface. Roll the dough to about ½-inch thickness. Using a 3-inch round cutter, cut out 12 donuts. You can re-roll scraps once to cut more, but don’t overwork the dough. Place the cut donuts on parchment-lined baking sheets, leaving space between each. Cover loosely.
Step 5: Second Rise: Let the shaped donuts rise again in a warm place for another 30-45 minutes, or until visibly puffy. This second rise contributes significantly to the final light texture of your homemade banana cream crunch donuts.
Step 6: Prepare the Banana Cream Filling: While the donuts rise, make the filling. In a medium saucepan, whisk together the mashed bananas, granulated sugar, cornstarch, egg yolk, and milk until smooth. Cook over medium heat, stirring constantly, until the mixture thickens and comes to a boil. Remove from heat and stir in the butter, vanilla extract, and salt until smooth. Transfer to a bowl, cover with plastic wrap pressed directly onto the surface to prevent a skin from forming, and chill completely in the refrigerator (at least 1 hour).
Step 7: Make the Crunch Topping: In a small bowl, combine the crushed vanilla wafers, melted butter, brown sugar, and cinnamon. Mix until well combined and crumbly. Set aside.
Step 8: Fry the Donuts: Heat about 2-3 inches of vegetable oil in a large Dutch oven or deep skillet to 350°F (175°C). Carefully lower 2-3 donuts into the hot oil (do not overcrowd the pan). Fry for 1-2 minutes per side, or until golden brown. Using a slotted spoon or spider, transfer the fried donuts to a wire rack lined with paper towels to drain excess oil. Repeat with remaining donuts. Allow donuts to cool completely before filling.
Step 9: Fill the Donuts: Once cooled, use a bismarck tip or a small, sharp knife to poke a hole into the side of each donut. Fill a piping bag fitted with the bismarck tip (or a regular round tip) with the chilled banana cream filling. Gently pipe the filling into each donut until it feels plump. Don’t overfill!
Step 10: Add the Crunch Topping: Dip the top of each filled donut into the crunch topping, gently pressing to adhere. Serve immediately and enjoy your homemade banana cream crunch donuts recipe!