Step 1

Add 4 cups water to a medium saucepan. Place on the stove over medium-high heat.

Step 2

While that's coming to a boil, rinse the lemons. Use a vegetable peeler to remove long strips of zest off of one, being careful not to get too much of the white pith.

Step 3

Peel 3 cloves garlic off and set aside. Cut the remainder of the head of garlic in half, along the equator (don't worry if it falls apart). Set aside with the lemon zest.

Step 4

Set four sprigs of the thyme aside. Add the rest of the thyme, lemon zest, halved garlic, and peppercorns to the water.

Step 5

Once the water comes to a boil, add the salt and brown sugar and stir until dissolved. Turn off the heat. Pour the mixture into a very large pot (big enough to hold 12 cups water and all 4 hens; I recommend at least an 8-quart pot). Add 8 cups cold water.

Step 6

Butterfly the hens. If there are giblets on the inside, remove and discard them. Use kitchen shears and start at the neck of the hen. Cut down both sides of the spine to remove the spine. Flip the hen over and open it up, then press down with your palm to flatten the bird out. Repeat with the remaining hens.

Step 7

Add the hens to the brine and refrigerate for 2 to 4 hours.

Step 8

1 to 24 hours before roasting, remove the hens from the brine to a wire rack over a rimmed baking sheet. Use paper towels to blot them as dry as possible, especially the skin. Return them to the fridge (uncovered). This allows the skin to dry out so it will brown and crisp.

Step 9

When it's time to cook the hens, remove the butter from the fridge and place in a small mixing bowl so it can start to soften.

Step 10

Take a large, heavy skillet or rimmed baking sheet and place it in the oven. It needs to be large enough that all four hens can fit in one layer. Preheat the oven to 425 F.

Step 11

Zest the second lemon. Measure 2 teaspoons of zest and add to the butter. Strip and chop the leaves from the reserved thyme sprigs, then add them to the butter. Grate or very finely chop the 3 reserved garlic cloves, and add them to the butter. Use a fork to mash it all together.

Step 12

Carefully separate the skin on the breast of the hen from the meat. Using your fingers, gently place butter under the skin. Turn the hen over and dot with more butter.

Step 13

Once the oven reaches 425 F, remove the hot pan. Place the hens in the pan skin-side down and return to the oven. Roast for 20 to 25 minutes, checking the skin and flipping once it browns. Flip the hens so they are skin-side up. Add ⅓ cup water to the bottom of the pan to prevent the juices from burning.

Step 14

Cook for another 10 to 20 minutes, until a thermometer in the inner thigh registers 165 F.

Step 15

Allow the hens to rest for 5 to 10 minutes before serving. Whisk the juices in the bottom of the pan and strain out any solids. Serve as a sauce with the hens.