For the collards: Place a large saute pan over medium-high heat. Add the bacon and cook until the fat is rendered but the bacon is not yet crisp, about 8 minutes. Add the collard greens, stock, onion powder, pepper and salt. Cook, stirring occasionally, until the greens have wilted down and most of the liquid has evaporated, 10 to 12 minutes. Scrape the greens into a small oval baking dish and spread into an even layer.
For the drop biscuit topping: Meanwhile, whisk together the flour, baking soda, sugar and salt in a medium mixing bowl. Whisk together the buttermilk and butter in a small mixing bowl. Pour the wet ingredients into the dry and stir until a dough comes together.
Spray an ice cream scoop with cooking spray and scoop the biscuits onto the collards, leaving some collards exposed. Each biscuit should be about 2 heaping tablespoons of dough. Bake until the greens bubble around the edges and the biscuits are golden brown, 25 to 30 minutes. Serve immediately.