Easy Smashed Chickpea Sandwich (Vegetarian Tuna Melt)

Ingredients

• 1 can (15oz) chickpeas, drained and rinsed
• 3-4 tbsp mayo
• 1 celery stalk, diced
• 1 small shallot, diced (or 1/2 small onion)
• 1 tbsp fresh dill
• 1/2 tsp salt
• 1/4 tsp black pepper
• a couple slices of bread
• a few slices of sharp cheddar cheese
• a handful of lettuce