Dice your medium peach into 1/2-inch pieces. Divide the peach pieces into two portions—you'll use half in the base mixture and half as a topping. I like to toss the first batch of peaches with the lemon juice immediately after cutting them; this prevents browning and adds a subtle brightness that complements the warm spices beautifully.

In a mason jar or container, combine the rolled oats, oat milk, maple syrup, vanilla extract, pumpkin pie spice, flaxseed, and salt. Stir until well mixed and no dry oats remain. Gently fold in the first half of the lemon-tossed peaches into this mixture, distributing them evenly throughout. This ensures the peaches soften evenly as the oats absorb the milk overnight.

Arrange the remaining peach pieces on top of the oat mixture—don't stir them in. This creates a beautiful presentation and keeps the top layer of peaches slightly firmer while the ones mixed into the base become soft and jammy. Cover the jar and refrigerate for at least 4 hours, though overnight is ideal for the best texture and flavor development.

Remove the jar from the refrigerator and give it a gentle stir to combine the layers. If the texture is too thick, add a splash more oat milk to reach your desired consistency. Top with the toasted pecans and serve immediately. I like to add the pecans right before eating rather than the night before—they stay perfectly crispy and add wonderful texture contrast to the creamy oats.