Pre heat oven to 190c
Line a rimmed baking sheet with baking/parchment paper and set aside
Lay one tomato sideways on a cutting board, then using a very sharp knife cut tomato into thirds as shown in the above image - then repeat for remaining tomatoes
Place slices of tomato on to prepared baking sheet, cut side up. Brush 1 teaspoon of olive oil on to cut side of tomatoes, then sprinkle with salt and pepper. Bake for 20 - 25 mins
Meanwhile, slice your fresh mozzarella ball into 8 slices and set aside (see notes), and place rocket/arugula into the base of your serving dish
When time is up, remove tray from the oven, and top each slice of tomato with a slice of fresh mozzarella - except for the tops or lids - just leave these as they are
Mix basil pesto with remaining 2 teaspoon of olive oil, brush tops of mozzarella slices with pesto oil. Keep any remaining pesto oil for serving
Return tray to oven (including tops/lids) and bake for another 5 mins
Remove from oven and place bottom (smallest) slices evenly on to your prepared bed of rocket/arugula, then top these slices with the middle ones, then finish with the tops/lids
Drizzle with any remaining pesto oil and serve immediately