Preheat a char-grill pan over high heat. Brush both sides of ciabatta with olive oil and grill, turning once, until charred and golden (2-3 minutes each side).
For smashed peas, blanch peas until tender and bright green (2-3 minutes for fresh and 1-2 minutes for defrosted frozen). Drain well, transfer to a bowl, add a generous pinch of sea salt and coarsely crush with a fork. Add remaining ingredients and check seasoning.
To serve, rub warm grilled ciabatta with cut garlic, top with smashed peas and pecorino, then drizzle with extra-virgin olive oil and season with cracked black pepper.