Heat grill or grill pan to medium-high. Brush bread slices on one side with 1 tbsp of the oil. Grill, oil side down, for 11/2 minutes. Brush with 1 tbsp oil and flip slices over. Grill another 11/2 minutes or until toasted and lightly marked. Transfer to a platter.
In a medium bowl, stir together ricotta, 1 tbsp of the chopped basil, the lemon zest and 1/4 tsp each of the salt and pepper.
Rub cut side of a garlic clove half on 4 of the bread slices. Repeat with remaining garlic clove halves and remaining grilled bread.
Gently toss cherry tomato slices with remaining 1 tbsp olive oil, remaining chopped basil, remaining 1/4 tsp each salt and pepper and the lemon juice.
Spread 1 tbsp of the ricotta mixture on each grilled bread slice. Top with a spoonful of the tomato mixture and garnish with basil leaves.