Rich, yet feather light. Make-ahead easy, yet impossibly elegant. Centerpiece worthy, yet made from nothing more than pantry staple ingredients. That’s why we love marquise au chocolat, France’s elevated chocolate mousse.

“It’s a paradox. Dense but light. Imagine molten chocolate being chilled but still somehow molten,” explains Aleksandra Crapanzano, whose newest book, “Gateau,” is an ode to Parisian home-style baking.

In France, this opulent treat has been enjoyed for centuries, particularly popular in the 1600s, when frozen sweets and chocolate were luxuries reserved for the wealthy. Many believe it was named after the Marquise de Sévigné, Marie de Rabutin-­Chantal, an aristocrat and writer famous for her love of cocoa.

Simultaneously indulgent and refined, the silky-smooth, egg white-­lightened mousse is timeless for a reason. And as we tinkered with recipes old and new, we found that one unorthodox ingredient produced a treat particularly velvety, while also ensuring the terrine stayed fluffy for days: heavy cream.

Traditionally, whipped egg whites get credit for creating the airy-­light texture of this loaf-shaped mousse. But they deflate more readily with time. In cream, however, air is suspended by sturdy fat molecules, as opposed to the fragile proteins that stabilize whipped egg whites.

The outcome? Cream-aerated marquise maintains its light, melt-in-your-mouth texture for days.

With lightness solved, we turned to richness. Typically, this is provided by egg yolks in combination with the chocolate. We kept that richness, but were able to achieve additional airiness by gently cooking the yolks with sugar and coffee, then whipping them to create a sabayon, a pale yellow custard that we later folded into the chocolate mixture.

Using coffee as the liquid enhanced the chocolate’s richness and depth, imbuing the whole dessert with fuller, more complex flavor. And incorporating a dash of cardamom, inspired by the spice-infused brews of Turkey, added alluring warmth and spice.

As for the finished terrine, it is as sleek, beautifully balanced and unapologetically chocolatey as the original, but markedly longer-lasting, creamy and infused with unique flavor.