In a small bowl, whisk the egg and the water together. Add to the bowl of an electric mixer. Add butter, flour, salt, yeast and mix powder. Using the dough hook attachment, knead 5-10 minutes to form a dough that is soft and elastic.

Place in a greased bowl. Cover with greased plastic wrap and a kitchen towel. Leave to rise until doubled in size, about 2 hours.

While it's rising let's make our cilantro crema. Place the chipotle in a bowl of boiling water and leave for 30 minutes. Drain. Combine crema, cilantro, lime juice, chipotle, salt and sugar in a food processor and blend well.

Transfer to a bowl and add beans. Stir well to thoroughly combine.

Place in refrigerator until ready to use.

Place a slice of parchment paper on a cookie sheet and spray with non stick spray.

Punch out air. On a lightly floured board, roll into a rectangle, 16x12".

Spread a thick layer of the crema on top, about 1/2 cup.

Starting at the long end, roll into a tight cylinder. Some of the crema will ooze out. That's fine and just discard it. Fold the ends underneath.

Using a sharp knife cut into 1-inch pieces. Place on the cookie sheet. Smash down to flatten them. Cover with a kitchen towel and leave to rise another 45 minutes.

Preheat oven to 350 F. Brush the tops with milk. Sprinkle sesame seeds and grated cheese on top.

Bake for 40 minutes, until they sound hollow when tapped.