Preheat oven to 400°. Drain baby artichoke hearts, reserving 1 tablespoon oil. Toss artichokes with oil on a rimmed baking sheet; bake until dark brown, about 15 minutes. To prepare hummus: Combine chickpeas, tahini, olive oil, garlic clove, fresh lemon juice, salt, pepper, and 1/4 cup water in a food processor; process until smooth. Add additional water, if needed. Spread 2 tablespoons hummus on each of 4 olive bread slices; layer each slice evenly with artichokes, sliced pepperoncini peppers, chopped sun-dried tomatoes, feta cheese. Arrange open-faced sandwiches on baking sheet; bake until warmed through, about 3-5 minutes.