Chef Johan Halsberghe has been making chocolate mousse for a long time. When Halsberghe was a kid in Belgium he spent hours hanging out with his "bompa" Jozef, a baker in Old Antwerp, learning the secrets of the stuff and whipping up his first batch when he was just eight years old. Young adulthood was spent learning and training all things culinary, and about a dozen years ago Halsberghe moved to New York City to be executive chef to the Belgian ambassador, where his chocolate mousse quickly became his most requested dish.

Today Halsberghe spends all of his time on his fluffy sweet treat, selling prepackaged containers at gourmet markets and specialty food stores around town, and, just last week, he opened what he's calling the "first chocolate mousse bar in America," named Mojo. Located on a side street in the East Harlem neighborhood where Halsberghe and his wife and partner Ana Sciena have lived for more than a decade, Mojo (it's a portmanteau of "mousse" and "Johan") is as much an all-day coffee shop as it is a dessert parlor, with seating both loungey and laptop-friendly in a bright, welcoming environment.

The decision to open in this mid-block spot, even though it's tough to stumble upon from the avenues, was a sensible one: in addition to being close to his home and family, Halsberghe has been using the space as his wholesale kitchen for several years now. And the build-out is impressive, with homey furnishings and contemporary design touches throughout. The golden spoon motif alludes to an old Belgian story that claims "when you die and go to heaven, you will be eating dessert with a golden spoon every single day for all eternity." (They sell golden spoons for $20.)

For the Mojo opening, Halsberghe is offering five different mousse flavors, all available scooped into cups, with optional crunchy-candy or fresh fruit toppings. The serving sizes are modest, but the mousse is rich and a double scoop satisfies. I sampled all five this past weekend, and my favorite combo, by a considerable margin, was the Dark Chocolate and Passion Fruit double, the deep intensity of the former pairing nicely with the bright tartness of the latter.

Other mousse options at Mojo include White Chocolate, Hazelnut Praline, and Matcha, which uses white chocolate as a base to cut some of natural bitterness in the green tea powder. None of these, by the way, are overly sugary, and the texture is consistently light and airy across all flavors.

If you're not in mousse mood, there are croissants and muffins from a nearby bakery available, and all sorts of coffee options. On Saturday, Sciena brewed a sludgy Snickerdoodle Latte for me, which went really well with a bucket of warm, freshly-made Pao de Queijo—those chewy, cheesy Brazilian tapioca bread balls that, in this case, are prepared daily for the shop by a friend of the couple.

Mojo Mousse Bar is located at 177 East 100th Street, between Lexington and Third Avenues, and is open weekdays from 7 a.m. to 6 p.m., and on weekends from 8 a.m. to 5 p.m. (917-331-3278; mojodesserts.com)