To make the biscuits, whisk together the flour, baking powder, baking soda, salt, pepper, sugar and chives in a medium bowl. Add the butter and cream cheese and work with your fingers to incorporate them into the flour mixture until it is unevenly crumbly. Make a well in the center and add the buttermilk. Use a fork to mix it into the dry ingredients.

Turn out the shaggy dough onto a lightly-floured work surface. Knead until it comes together and press it into a circle about 1½ inches thick. Use a floured biscuit cutter (1½ to 2-inches) to cut biscuits. Press together the dough scraps and repeat until no dough remains. Place biscuits on a small cookie sheet and refrigerate until ready to bake.

Heat oven to 400º. Melt 2 tablespoons of butter in a medium saucepan set over medium heat. Add the onions and cook until starting to soften, 3-4 minutes. Add the garlic and continue cooking an additional minute. Add the carrots, zucchini and peas and cook for another 3 minutes. Transfer to a bowl and set aside.

Melt the remaining 4 tablespoons butter in the same saucepan over medium heat. Whisk in the flour. The mixture will be very thick. Cook for 1 minute, then reduce heat to low and whisk in the chicken broth. Once no bits of flour remain, whisk in the milk and cream cheese. Increase to medium-low heat and continue cooking until the cream cheese has melted. Add the chicken, lemon and nutmeg. Taste and adjust seasonings as needed. Stir in the vegetables.

Transfer filling into a 9×13-inch baking dish. Place the biscuits on top of the chicken mixture and brush with milk. Bake for 20-25 minutes, until the biscuits are golden and the filling along the sides of the dish is bubbling. Allow to cool slightly before serving. To reheat, cover dish with foil and bake at 300º for about 15 minutes.