Melt the butter in a large skillet over medium-high heat. Add the agave, cinnamon, nutmeg, salt and apples; mix well. Cover and let simmer until the apples begin to soften, 7 minutes. Add the peaches, stir, and continue cooking until the fruit begins to caramelize and thicken, 8 minutes. Add the lemon zest and let simmer for another minute.
Serve the compote over vanilla ice cream and top with whipped cream if using.