Position a rack in the lower third of the oven and preheat to 400 degrees F. Make the pumpkin seed pesto: Heat 3 tablespoons olive oil, the pepitas, 1/2 teaspoon salt and a large pinch of paprika in a large skillet over medium heat. Cook, shaking the skillet, until the seeds begin popping and some turn brown, about 5 minutes. Remove from the heat and let cool completely. Transfer the seeds and oil to a food processor; add 1/2 cup water, the parsley, scallions, lemon juice and 1/4 teaspoon salt and pulse until pureed. Remove about 3 tablespoons of the pesto for the hens and set aside the rest for serving.
Slide your fingers under the breast skin of each hen to loosen. Slide 2 heaping teaspoons of the pesto under the skin of each hen, then rub the skin to distribute the pesto.
Mash the garlic and 2 teaspoons salt with the flat side of a chef's knife to make a paste. Combine with the remaining 2 tablespoons olive oil and 1 teaspoon paprika in a bowl, then rub all over the hens. Refrigerate, uncovered, at least 2 hours or overnight.
Put the hens on a rack in a shallow roasting pan or rimmed baking sheet and tie the legs together with kitchen twine. Roast, rotating the pan halfway through, until the skin is golden brown and a thermometer inserted into the thickest part of the thigh registers 170 degrees F, about 1 hour. Let rest 15 minutes, then cut each hen in half. Serve with the reserved pesto.