Make the dough:

1. Soften the butter. Remove butter from the fridge and allow it to soften in room temp for 30-45 minutes. You’ll know when the butter is soft when you are easily able to press down your finger on it. 
2. In the bowl of a stand mixer, combine the bread flour, non-dairy milk, salt, instant yeast, and sugar. Attach the bowl to the stand mixer, and with the dough hook attachment start mixing the dough at the lowest speed. 
3. When it starts looking like a shaggy dough, add in the softened butter, 1 tablespoon at a time until fully incorporated. Then increase the speed to 2 and continue to knead for 10 minutes until you get a smooth dough.
4. Remove the dough from the bowl, and shape it into a smooth ball. (The dough will be a bit stickier, so if it sticks too much rub a bit of oil in your hands.) Gather the ends of the dough to the middle, and pinch them together. Flip it over with the seam side down and use your hands to move it around in a circle. Tucking the dough underneath itself, pull their tops taut.
5. Place the shaped dough into a large lightly oiled bowl (or just use the same bowl). Cover with a damp cloth or plastic and set it in a warm spot. Allow it to rise for 1 1/2 hours, then transfer it to the fridge and let it continue to rise for 30 more minutes. See notes
6. Meanwhile, cut up parchment paper into 10 squares, about 4×4 inches, and set them aside. This will act as a vessel to transfer the donuts to the work surface and into the pot.
7. Punch the dough down to release the gas, and transfer it to a work surface. Evenly divide the dough into even 10 pieces. If you are using a food scale, make sure they are equal in weight. Shape each dough into a smooth ball and place them on the parchment paper squares. Cover with a damp cloth set it in a warm spot, and let it rise once more for 30 minutes – 1 hour, or until doubled in size and puffy.
8. Preheat the oil in a large pot or deep fryer at a steady 375° F or over medium heat. You’ll need a lot so it floats and doesn’t touch the bottom. When the dough has doubled in size, place 2-3 pieces of dough  into the oil (yes, along with the parchment paper, it will naturally release from the dough when it hits the oil. Just remember to remove it from the pot, do not leave it in the oil.). 
9. Fry for about 30-45 seconds or until golden brown on each side. See notes
10. Place donuts on a wire cooling rack with a baking sheet underneath to drain the excess oil. 
11. Prep a mixing bowl with a ½ cup of sugar. While the malasadas are still hot, carefully toss them in the sugar. Make sure each piece is covered. Allow them to fully cool.

Make the filling:

1. In a blender, combine the soy milk, vanilla, sugar, and cornstarch. Blend all the ingredients until smooth. Pour the mixture into a saucepan and place it over medium heat. 
2. Stir constantly until the mixture has thickened, about 8-10 minutes.
3. Remove the pan from the heat, and mix in the melted butter until well combined.
4. Transfer the custard mixture to a heatproof bowl and allow it to cool down to room temp. Once it has cooled down, cover with plastic wrap so that it is in direct contact with the custard. Refrigerate for 30 minutes to set.

Assembly:

1. Before using the custard as a filling, whisk vigorously until it becomes creamy again and smooth.
2. Use a piping bag fitted with a medium round piping tip and fill it with the custard.
3. Take a knife or a chopstick to poke a hole in the center of the donut. Wiggle it around inside the malasadas to create a pocket for the filling. 
4. Fill each donut with the custard, slowly pulling out until it slightly overflows at the top. 
5. Serve immediately or let cool to room temperature and store in an airtight container for up to 2 days. Enjoy!