Preheat the oven to 375°F (190°C).

Make the filling. In a large pot over medium-high heat, heat the butter. Once the butter is melted, add the onion and garlic. Sauté, reducing the heat as needed, until the onion is translucent, 2 to 3 minutes. Add in the flour, and stir to combine. It should form a paste. Simmer for about 1 minute. Pour in the vegetable broth, and whisk to combine, making sure there are no lumps of flour.

Add the frozen broccoli, bay leaves, thyme, nutmeg and a pinch of salt and pepper. Bring to a simmer, reduce the heat to medium-low, and let it simmer for 10 to 15 minutes, stirring frequently.

Make the cashew cream. Drain the soaked cashews, and add them to a blender with the milk and a pinch of salt and pepper. Blend until the mixture is completely smooth.

Remove the bay leaves and thyme sprigs from the pot, and pour the cashew cream into the pot. Stir to combine. Add the Cheddar, and stir until the cheese has melted. Taste and adjust seasonings.

Pour the filling into a square 9 x 9–inch (23 x 23–cm) baking dish or rectangular 9 x 13–inch (23 x 33–cm) baking dish. Set aside.

Make the biscuit topping. In a large mixing bowl, sift together the flour, baking powder and baking soda. Stir in the black pepper, salt and Cheddar.

Add dollops of the cold butter into the bowl, and begin to press and squeeze the butter into the dry mixture using your fingers or a fork. You want the butter to be evenly distributed and resemble sand.

In a small mixing bowl, combine the milk and lemon juice. Whisk together. Pour the milk mixture into the mixing bowl with the dry ingredients and butter. Stir to combine, and bring together into a dough ball.

Turn the dough out onto a floured surface, adding a little more flour if the dough is still sticky. Roll it out so it is about ½ inch (1.3 cm) thick, and cut large circles or squares out of the dough. You want enough to cover the filling.

Put the biscuits on top of the filling in the baking dish. Brush the tops of the biscuits with a little melted butter. Bake for 25 to 30 minutes, or until the biscuits are golden brown and cooked through. Serve immediately.