Step 1

Pulse the garlic in a food processor fitted with the blade attachment until coarsely chopped, 5 to 6 pulses. Add 1/2 the basil and pulse until the leaves are coarsely chopped, 5 to 6 pulses. Add the remaining basil and pine nuts. Pulse into a coarse paste, 10 to 12 pulses. Add the oil and 1/4 teaspoon of the salt. Pulse until just combined into a coarse paste; set aside.

Step 2

Season the chicken breasts with the remaining 3/4 teaspoon salt and the pepper. Place the chicken in a 3- to 5-quart slow cooker. Add 3 tablespoons of the pesto and toss to combine. Place the remaining pesto in the refrigerator.

Step 3

Cover and cook on the LOW setting until the chicken is cooked through, registering 165°F on an instant-read thermometer, 1 1/2 to 2 1/2 hours. If desired, stir the tomatoes in during the final 30 minutes of cooking.

Step 4

Uncover and stir in the reserved pesto. To serve, toss with cooked pasta, serve on a sandwich bun, tuck in a wrap, or serve on top of cooked rice or cauliflower rice.