Preheat the oven to 400°F. Add the farro to a small saucepan over medium-high heat. Toast in the dry pan, shaking occasionally, until the grains are fragrant, about 2 to 3 minutes. Add 1½ cup water, a pinch of salt, and bring to a boil. Reduce heat to low, cover, and simmer farro until tender, about 22 to 25 minutes. Drain any remaining water and return farro to the pan.
Melt the leeks
Place a large nonstick skillet over low heat with 1 tbsp olive oil. Add the sliced leeks, sprinkle with salt and pepper, and cook, stirring occasionally, until soft, about 8 to 10 minutes.
Roast the chickpeas
Drain and rinse the chickpeas. Add the chickpeas to a baking sheet and toss with 1 tbsp vegetable oil and the French mustard & herb blend and a pinch of salt. Roast until crispy and browned in places, about 12 to 15 minutes.
Roll the cheese
Finley chop the pistachios. Roll the Treeline cheese into 4 small balls. Add the chopped pistachios to a plate with a pinch of salt and pepper. Roll the cheese in the nuts to coat.
Prepare the salad
Halve the lemon and cut half into wedges. Thinly slice the apple and add it to a large bowl. Add the arugula, 1 tsp olive oil, juice from just half the lemon, and a pinch of salt and pepper. Toss the apple arugula salad.
Stir the farro and butter into the skillet with melted leeks, season with salt and pepper. Divide the apple arugula salad between large bowls and top with the farro, crispy chickpeas, and pistachio cashew cheese. Serve ancient grain bowls with lemon wedges.