Mix paprika, cumin, salt, cayenne, cinnamon, turmeric and black pepper together in a small bowl.
Place chicken thighs in a resealable plastic food bag. Sprinkle paprika mixture over chicken thighs; massage the bag to coat chicken evenly.
Heat oil in a tagine over medium heat. Add chicken; cook until browned, 2 to 4 minutes per side. Transfer to a plate. Cook and stir fennel, onion and garlic in the tagine. Stir in half of the chickpeas, chicken stock, 1/2 of the green olives, harissa, 1/2 of the preserved lemon and fresh ginger.
Lay chicken over chickpea mixture; sprinkle remaining olives on top. Scatter cherry tomatoes on top. Cover and simmer over medium-low heat until chicken is tender, 45 minutes to 1 hour.
Combine remaining chickpeas with 2 tablespoons of sauce from the tagine in a food processor or blender; blend into a thin paste.
Transfer chicken to a serving dish. Stir chickpea paste into the tagine. Simmer until flavours combine, about 5 minutes. Spoon mixture over chicken.
Garnish with remaining preserved lemon and toasted almonds.