Add in the milk, eggs, butter, and avocado oil. Combine everything well.
Pour mixture into a greased 9x13 baking pan. Bake for 30 minutes or until a toothpick comes out clean.
Remove from heat and let cool slightly. Break up cornbread with a spatula into bit sized pieces and set aside. It's best if you can do this step the day before.
Cornbread Dressing
Raise the temperature of the oven to 400°.
In a large skillet over medium-high heat, sauté the onions and celery in the butter along with the dried sage, dried thyme, kosher salt, and pepper.
Once the onions and celery are soft, add those to the crumbled cornbread and toss to combine.
Add the broth and cream and stir to combine all of these ingredients. This is where I taste to see if I need to add any salt or pepper - before the eggs are added.
Once you determined the seasonings for the dressing are good, add in the slightly beaten egg and mix in well. This mixture should be very, very moist, but not soupy.
Pour the cornbread dressing into a greased 9x13 baking dish and bake at 400° for about 45-50 minutes or until the dressing is just set and the edges are golden brown.