- To prepare the stew, whisk the flour, salt, allspice, and cayenne in a small bowl and set it aside. Preheat the oven to 325F.
- Melt the butter and heat the olive oil in a Dutch oven over medium-high heat until it shimmers. Working in batches so that you don’t overcrowd the pan, cook the beef cubes, turning 2-3 times until they are walnut brown all over, about 10 minutes per batch.
- Reduce the heat to medium and return all the beef to the pot. Sprinkle the reserved flour mixture over it and cook while stirring until fragrant, about 2 minutes. Add the stock, coffee, and the bay leaf. Bring to a boil and use a spoon to scrape the bottom of the pot clean.
- Cover the pot and transfer it to the oven for 30 minutes. Add the onion, carrots, potatoes, and pepper, and continue cooking in the oven until the beef and the vegetables are tender to the bite, 1 to 1 1/4 hours for a total of 1 1/2 to 1 3/4 hours.
- Meanwhile, make the biscuit dough. Whisk together the all-purpose flour, whole-wheat flour, baking powder, baking soda, sugar, and salt in a large mixing bowl. Using your fingertips or a pastry blender, cut the butter into the flour mixture until it resembles coarse meal. Make a well in the center of the flour and pour in the heavy cream and buttermilk. Stir until the dry ingredients absorb all the liquid and you can collect the dough into a ball.
- Remove the stew from the oven and taste it for salt and pepper. Remove and discard the bay leaf. Whisk the cornstarch with 3 tablespoons cold water and stir it into the stew.
- Using a 1/3 cup measure as a scoop, portion the biscuit dough and plop the mounds in a single layer on top of the stew. (They’ll be touching.) Put the stew back in the oven and bake until the biscuit tops are tinged with brown, an additional 30 to 35 minutes.