Prep the oven and pan: Preheat to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease well.

Dice the peaches: Peel if you like (optional). Cut into small 1/4-inch cubes so they distribute evenly. If using frozen, thaw and pat dry.

Make the peach mix: Toss peaches with 1–2 teaspoons sweetener and 1 teaspoon lemon juice. Set aside to draw out a little juice and enhance flavor.

Whisk dry ingredients: In a large bowl combine 2 cups almond flour, 2 tablespoons coconut flour, 1/2 cup granulated sweetener, 2 teaspoons baking powder, 1/2 teaspoon cinnamon, a pinch of nutmeg, 1/4 teaspoon salt, and 1/4 teaspoon xanthan gum (optional).

Mix wet ingredients: In another bowl whisk 3 large eggs, 1/3 cup melted butter (slightly cooled), 1/3 cup unsweetened almond milk, and 1 teaspoon vanilla.

Combine: Pour wet into dry and stir until just combined. The batter will be thick but scoopable. Gently fold in the peaches, draining off any excess juices first.

Make the crumble: In a small bowl, combine 1/2 cup almond flour, 2 tablespoons granulated sweetener, 1/2 teaspoon cinnamon, a pinch of salt, and 2 tablespoons cold butter cut into small cubes. Work with your fingertips until a sandy, clumpy texture forms.

Fill the tin: Divide batter evenly among the 12 cups (a heaping 1/4 cup each). Sprinkle crumble over the tops, pressing lightly so it adheres.

Bake: Bake 20–24 minutes, until the tops are golden and a toothpick comes out clean or with a few moist crumbs. If using allulose, watch closely near the end; it browns faster.

Cool: Let muffins cool in the pan 10 minutes, then transfer to a rack to cool fully. This helps them set and prevents crumbling.