Sprinkle yeast over warm water in a mixer fitted with a paddle, (or using beaters). Add sugar and egg and blend to combine. Add flour and salt and mix until flour is combined. Increase speed and blend until dough is stretchy and elastic, about 4 minutes. Add butter and blend until incorporated. Set dough in an oiled bowl, covered with plastic wrap and let rise for 30 minutes.
Divide dough into 8 greased baba tins (they should fill halfway). Let rest uncovered until doubled in size, about 30 minutes.
Preheat oven to 350 °F. and bake babas for about 20 minutes, until golden brown. Unmold babas while warm then cool completely.
For soaking syrup, heat water and honey with rosewater or orange blossom water (if using), until fluid. Stir in rum. While syrup is warm, Dunk babas in syrup, turn over and remove with tongs, and set onto a cooling rack over a baking tray to drain. Once cooled, babas can be filled.
For cream, beat cream cheese, honey, cream and vanilla until smooth and pipeable. Fill a piping bag and poke a hole in the bottom of each baba. Pipe cream into each. Sprinkle tops of babas (they will rest on their side) with chopped pistachios and chill until ready to serve.