Separate chard stems and leaves. Chop the stems into ¼-inch pieces and the leaves into ½ -inch pieces. Set aside.
Heat 2 tablespoons butter in a medium skillet over medium heat. When it foams, add the shallot, chard stems, fennel, fennel seeds, chile flakes, and a pinch of salt. Cook, stirring, for about 3 minutes. Stir in the garlic and sage and cook for 2 more minutes.
Add the pork, stirring to combine it with the aromatics. Spread meat into a single layer, increase heat to medium-high, and cook without moving for about 3 to 4 minutes to brown the meat. Reduce heat to medium, flip and continue to cook, stirring, for another minute.
Add wine, bring to a simmer, and cook until the liquid has evaporated a bit, 2 to 3 minutes. Add the chard leaves and cook, stirring, until they have wilted into the mixture.
Reduce heat to medium low and add the cream. Stir to combine, taste and adjust seasoning. Simmer for 2 to 3 more minutes to reduce the sauce. Set aside.