Step 1: In a small bowl, combine warm milk and instant yeast. Let it stand for 5-10 minutes until it becomes foamy.
Step 2: In the bowl of a stand mixer fitted with a dough hook, combine bread flour, sugar, and salt.
Step 3: Add the yeast mixture and egg yolks to the dry ingredients. Mix on low speed until a shaggy dough forms.
Step 4: Gradually add the softened butter, one tablespoon at a time, allowing each piece to be fully incorporated before adding the next. Knead on medium speed for 10-15 minutes until the dough is smooth and elastic.
Step 5: Place the dough in a greased bowl, cover with plastic wrap, and let it rise in a warm place for about 2 hours or until doubled in size.
Step 6: Punch down the risen dough and divide it into 12 equal portions (approx 70-80g each).
Step 7: Flatten each portion into a rectangle. Spread about 2 teaspoons of mango jelly in the center, leaving the edges clear.
Step 8: Roll the dough into a log, sealing the edges tightly. Coil the log into a spiral shape and place in greased ensaymada molds or a muffin tin.
Step 9: Cover the shaped buns and let them rise again for 45-60 minutes until puffy.
Step 10: Preheat your oven to 350°F (175°C). Bake the buns for 18-22 minutes or until lightly golden brown.
Step 11: Allow the buns to cool slightly. While still warm, brush generously with softened butter, then dip or sprinkle with sugar and a mountain of grated cheddar cheese.