• Preheat the oven to 350°F.
• Pour the olive oil into a large skillet and place over medium heat. Once the oil is shimmering add the onions and a pinch of salt. Sauté the onions until just translucent. Stir in the garlic and sauté until fragrant. About 30 seconds more. Add the mushrooms and cook until well-browned and softened. About 5 minutes.
  2 tbsp olive oil, 1 yellow onion, 2 cloves garlic, 454g (1 lb) cremini mushrooms
• Remove the mushrooms and onions from the skillet using a slotted spoon. Add the butter to the skillet and melt. Whisk in the flour to form a roux. Slowly whisk in the white wine, and milk to form a thick bechamel. Return the mushrooms and onions to the skillet along with the mustard, horseradish, and salt. Stir to combine. Take the skillet off of the heat and set it aside.
  ¼ cup unsalted butter, ¼ cup all-purpose flour, ½ cup white wine, 1 cup whole milk, 1 tbsp Dijon mustard, 1 tbsp prepared horseradish, ½ tsp kosher salt
• Place a large pot of water over high heat and bring to a boil. Once the water reaches a rolling boil, salt it generously and add the green beans. Cook for no more than 3 minutes before transferring to an ice bath to stop the cooking process.
  400g (14oz) green beans
• Drain the green beans and place them in the mushroom bechamel. Toss to coat. Transfer the beans to an 11x7" casserole dish and bake for 15-20 minutes. Take the casserole out of the oven and top with fresh pakora onions (see below). Serve immediately.
  1 batch Pakora Onions

For the Pakora Onions **

• In a large bowl whisk to combine the chickpea flour, baking powder, and salt. Add the chilis, cilantro, and onions. Using your hands, toss to coat the ingredients in the flour mixture and tease the onions apart. Slowly stir in the warm water until a batter forms. It should be roughly the consistency of pancake batter.
  2 cups chickpea flour, ½ tsp baking powder, 1 tsp kosher salt, 2-3 green chilis, ¼ cup fresh cilantro, 1 yellow onion, 1 cup warm water
• Heat the oil in a large skillet until shimmering. Using tongs, grab onion pieces and add them to the oil. It's fine if I few stick together and form clusters. Don't overcrowd the pan. Fry until golden on both sides, this should go fairly quickly.
  1 cup neutral oil
• Transfer the finished pakora onions to a plate lined with a paper towel to drain. Sprinkle the onions with additional salt and place them on top of the green bean casserole fresh from the oven. Serve immediately.