In a bowl, stir together yeast, sugar, and water; set in a warmer place to activate. Let sit until it gets thick and foamy - about 15 to 20 minutes.
In the meantime, add flour to your mixer's bowl; make a well in the middle and add warm milk to the well, vegetable oil, salt, and eggs. Don't mix until you've added in the prepared yeast.
Pour yeast mixture into the flour mixture; using a large spoon, mix it all together to combine.
Then, attach the dough hook to your stand mixer and finish kneading for about 2 to 3 minutes, or until dough starts to separate from the bowl. If dough is too dry, add a tablespoon of milk, if it's too wet add more flour, 1 tablespoon at a time. Dough shouldn't be too sticky, but you also don't want it to be dry.
Spray a large mixing bowl with cooking spray and sprinkle it with a bit of flour to prevent sticking.
Transfer prepared dough to the oiled bowl ; fold dough into a circle; add more flour to the bowl and a sprinkle of flour on top of the dough ball.
Cover with plastic wrap and let rise for 30 minutes. It's best (and faster) to let the dough rise in a warmer spot.
Combine feta cheese and ricotta cheese in a bowl; set aside for later.
Preheat oven to 400˚F.
Turn the dough over to a flour dusted work area and fold it on all sides; then, cut in half. Cut each half in 3 parts so you have a total of 6 pieces. Fold all pieces into small balls. Keep them covered.
Take a ball of dough and lightly punch it down to spread and then roll it out into a round circle the size of about a medium pizza. Make sure to flour your work area often so the dough does not stick.
Cut into 8 to 12 slices, depending on the size of the dough’s diameter.
Add a tablespoon of the ricotta/feta cheese mixture to each slice. Place the filling at the top of the slice, right in the center.
Roll them up; pull the sides of the widest part at the top and tuck them inward, right over the filling, and continue to roll.
Repeat with the rest of the dough.
Transfer kifli/rolls to baking sheets; place a pat of butter on top of each roll.
Bake for 5 minutes at 400˚F.
Prepare the glaze; combine eggs and water in a small bowl and beat to combine.
Remove Kifli from oven and brush with egg glaze; sprinkle with sesame seeds and continue to bake for 11 to 13 more minutes, or until golden.