Purée 1 cup basil leaves and 1/3 cup oil in a blender until smooth and only tiny flecks of basil remain.
Set a fine-mesh strainer over a large bowl. Strain mixture into bowl, pressing on solids to extract as much oil as possible; discard solids in strainer.
Add shallot, garlic, lemon zest, and lemon juice to basil oil; whisk to blend. Season to taste with salt and pepper.
Slice tomatoes into assorted wedges, rounds, and cubes; add to bowl with dressing. Toss to coat; let marinate at room temperature while preparing croutons.
Cut bread into 2cm thick croutons.
Place in bowl, season with salt and pepper and toss with 1/3 cup of oil till coated.
Grill bread in hot oven til golden brown, about 10 minutes.
Add bread and remaining 1/2 cup basil leaves to bowl with tomato mixture; toss to coat. Season panzanella to taste with salt and pepper and serve.

Ingredients
Directions
Purée 1 cup basil leaves and 1/3 cup oil in a blender until smooth and only tiny flecks of basil remain.
Set a fine-mesh strainer over a large bowl. Strain mixture into bowl, pressing on solids to extract as much oil as possible; discard solids in strainer.
Add shallot, garlic, lemon zest, and lemon juice to basil oil; whisk to blend. Season to taste with salt and pepper.
Slice tomatoes into assorted wedges, rounds, and cubes; add to bowl with dressing. Toss to coat; let marinate at room temperature while preparing croutons.
Cut bread into 2cm thick croutons.
Place in bowl, season with salt and pepper and toss with 1/3 cup of oil till coated.
Grill bread in hot oven til golden brown, about 10 minutes.
Add bread and remaining 1/2 cup basil leaves to bowl with tomato mixture; toss to coat. Season panzanella to taste with salt and pepper and serve.