Preheat your oven to 190°C / 375°F.
Place the pepper halves cut-side up in a lightly oiled roasting tin. They should fit snugly enough to hold their shape but not be crammed in.
Fill each pepper half with the cherry tomatoes or tomato quarters. Tuck the sliced garlic among the tomatoes.
Drizzle generously with extra virgin olive oil, using about half to one tablespoon per pepper half. Season with freshly ground black pepper. Do not add salt yet as the anchovies are already salty.
Roast for 50 minutes to 1 hour, until the peppers are completely tender and beginning to char slightly at the edges, and the tomatoes have collapsed and caramelised.
Remove from the oven and allow to cool slightly. Transfer to a serving platter and pour over all the roasting juices from the tin. Place 2 anchovies over each pepper in a cross pattern and finish with fresh basil leaves and a pinch of flaky sea salt if needed.
Serve warm or at room temperature with crusty bread.