Preheat the oven to 180C/356F. Line a baking sheet with parchment paper.
Add the carrots, sweet potatoes and parsnips onto the baking sheet, drizzle with olive oil and toss to combine.
Roast for 15 minutes (they will continue the cooking process during the galette baking).
While the vegetables are roasting, prepare the galette dough.
Add the flour and butter into the food processor and pulse to obtain a crumble.
Add the water and salt and pulse to incorporate and create a dough.
Cover the dough with foil and refrigerate.
Remove the vegetables from the oven and transfer into a large bowl.
Add the chickpeas, peas, cranberries, cheese, garlic and spices, and toss to combine.
Remove the dough from the refrigerator and add onto a floured surface.
Roll into a 12 inch circle, about 1/4 inch thick, and transfer onto the baking sheet.
Arrange the filling on top of the dough, leaving a 2-inch border around the edges.
Fold up the dough border over the filling, and brush with egg yolk to get a golden crust.
Bake for 30 minutes until golden.
While the galette is baking, prepare the caramelised onion.
Cook the onion in a non-stick skillet with a tablespoon water, over medium heat, stirring continuosly, until translucent
Add the balsamic vinegar, stir to combine and cook two more minutes over low heat. Turn off the heat and set aside.
Cut into slices and serve warm, topped with caramelised onion and drizzled with honey.