Preheat oven to 425˚. Combine blackberries with honey and lemon zest. Roast berries until tender, 15 to 18 minutes. Remove from oven, lightly smash/break apart and let cool slightly.
Slice the pieces of bread in half, on the diagonal, and spread a small bit of butter on top. Place in oven and let toast until golden and crisp.
In a small bowl, whip together goat cheese, honey, salt and pepper.
Smear pieces of bread with a smear of goat cheese, a spoonful of blackberries, and finish with a leaf of mint.