Using a heavy bladed knife, cut through the cartilage and split the breast.
Then lay the blade about 1/4” to the side of the spine and cut through the rib cage, and down the entire length of the spine. Repeat on the other side of the spine.
This will give you two nice halves to work with.
Try one chicken with your favorite rub, cover with a generous coating. Let sit for about 30 minutes before cooking. This gives us time to prep another chicken that we are going to set up to self-baste while it cooks. We can start pre-heating the smoker to 375°F.
In a bowl put 6 tablespoons soft butter, 1 Tablespoon minced garlic, 1 teaspoon each dried sweet basil and kosher salt.
Stir all together to make a paste
Take one fourth of the paste and slip it under the skin on each breast and each hind quarter. Coming from where the spine and back were removed should be easy to find a spot to put the butter mix inside with a long handled teaspoon.
Flatten the butter mix around under the skin by pressing gently on it.
Place the chickens on your smoker rack spaced evenly.
Cook for 45-50 minutes depending on the size of your chickens, looking for an internal temperature of 160°F in the white sections and 170°F in the dark sections. Let rest a few minutes and serve.