Bring a large pot of water to a boil.

Wash, prepare, and chop the vegetables for the filling (cauliflower, celery, carrots, onion).

Preheat the oven to 450F.

Lightly flour a clean work surface.

In a spouted mixing bowl, combine the plant-based milk and the vinegar. Let stand for 5 minutes to create vegan buttermilk

In a large mixing bowl, whisk together the flour, baking powder, and salt.

Add the cold butter and use your fingers or a pastry cutter to "cut" the butter into the flour mixture until it's well incorporated and dispersed throughout the flour mixture.

Create a well in the center of the flour mixture. Stir in the "buttermilk" and continuing stirring until just combined.

The dough should be moist and malleable and only the slightest bit tacky. If the dough is too wet, add more flour a little bit at a time.

Turn the dough out onto the floured surface.

Fold the dough over on itself a few times—be careful not to knead, just fold and press. Form into a 1-inch-thick layer.

Use a biscuit cutter or the rim of a juice glass to punch out about 6 biscuits. Gently reform the dough scraps and repeat until you've used up as much of the dough as possible. You should have 8 to 10 biscuits in total.

Set aside and get to work on the filling.

Add 3 cups of the cauliflower florets to the pot of boiling water, and boil for 5 to 7 minutes, or until fork-tender (boiling time will depend on the size of your florets). Drain and set aside.

While the cauliflower boils, melt the butter in a large but shallow oven-safe stockpot or dutch oven over medium-high heat.

Add the remaining 3 cups cauliflower florets along with the onion, carrots, celery, thyme, and rosemary. Sauté for 8 to 12 minutes, or until the vegetables begin to soften and caramelize, stirring occasionally. You want the cauliflower to be tender at this point.

Add the peas and the cauliflower cream and continue to cook for 2 to 4 minutes, or until the peas are warmed through and the cauliflower cream is hot and bubbly, stirring gently but constantly to prevent sputtering and splashing.

Turn off the heat. Taste and adjust seasonings, adding more salt and pepper to taste (I add ½ teaspoon more salt and a few generous twists of freshly ground black pepper).

Use a spatula or the back of a spoon to compact and spread the filling into an even layer in the dutch oven. Arrange the biscuits on top of the filling and brush them with the melted vegan butter.

I like to finish the biscuits with a sprinkle of smoked flaky sea salt before popping the dish in the oven, but this step is totally optional.

Bake for 15 to 20 minutes, or until the filling is hot and bubbly; and the biscuits are golden-brown on top and baked through.

Let cool for 5 minutes or so. Serve warm, ensuring that each helping gets a biscuit.