5 tablespoons cold unsalted butter, cut into small pieces
3/4 cup half-and-half
1/2 pound slab bacon, cut into 1-by-1/2-inch sticks
1 large sweet onion, thinly sliced
3 garlic cloves, minced
4 ounces spicy andouille sausage, halved lengthwise and sliced 1/4 inch thick
4 cups Turkey Stock or chicken stock
4 pounds collard greens—thick stems and inner ribs removed, leaves cut into
1 cup plus 2 tablespoons half-and-half
2 tablespoons cornstarch dissolved in 1/4 cup water
Salt and freshly ground pepper
In a food processor, pulse the flour, cornmeal, baking powder, sugar and salt. Add the butter and pulse until it's the size of small peas. Add the half-and-half and pulse just until the dough comes together. Transfer the dough to a lightly floured work surface and knead 2 or 3 times. Flatten the dough slightly and roll it out to a 10-inch square. Cut the dough into 2-inch squares and refrigerate on a baking sheet.
In a large pot, cook the bacon over moderate heat until golden and the bacon fat is rendered, about 8 minutes. Using a slotted spoon, transfer the bacon to a plate. Discard all but 1 tablespoon of fat from the pot. Add the onion and garlic and cook over moderate heat, stirring, until softened, 6 minutes. Add the bacon, andouille and 3 cups of the Turkey Stock and bring to a boil over high heat. Add the collards in 3 batches, stirring so each batch wilts before adding more. Cover and simmer over low heat until the collards are very tender, 30 minutes.
Preheat the oven to 375°. Add 1 cup of the half-and-half and the remaining 1 cup of stock to the collards and bring to a boil. Stir the cornstarch slurry and add it to the pot. Cook, stirring, until thickened, 2 to 3 minutes. Season with salt and pepper.
Transfer the collards to a large ceramic or glass baking dish. Top with the biscuit squares, overlapping them slightly, and brush the tops with the remaining 2 tablespoons of half-and-half. Season the biscuits well with pepper and bake for 50 minutes, or until the greens are bubbling and the biscuits are golden. Let rest for 20 minutes before serving.
The recipe can be prepared through Step 3 one day ahead; refrigerate the biscuits and collards separately.