Process cashews in a food processor until fine and flour-like. Add almond flour, sugar, avocado oil, cinnamon, and allspice—pulse to combine, but don’t over-pulse. Set aside.
Preheat grill (or grill pan on stovetop) to medium-high heat. Place halved peaches in a bowl, then toss with a generous amount of avocado oil (enough to coat the fruit), lemon juice, cinnamon, and a drizzle of honey. Whisk together lemon juice, honey and cinnamon in a bowl. Add peach halves and gently toss to coat.
Clean grill thoroughly, then lay peaches face down and grill until softened and caramelized, about 5 minutes. When soft, flip with tongs and grill on other side, 2-3 minutes.
Preheat broiler to 450 degrees and set your oven rack in the second-to-highest position. Lay grilled peaches face up in a 9x13 baking dish. Spoon a generous amount of streusel onto each peach half. Broil until lightly browned, about 1-3 minutes depending on the strength of your broiler (mine is intense). Serve drizzled with additional honey, almonds, raspberries, and gelato.