Cut 8 medium fresh yellow peaches, about 2.5 pounds, into uneven 1/2-inch wedges at 68°F to 72°F. Fold them with 1/2 cup light brown sugar, cornstarch, lemon juice and vanilla. Add 3/4 teaspoon cinnamon and 1/8 teaspoon salt. Use broad bottom-to-top turns for 30 seconds. Then let the peaches stand exactly 10 minutes so their juices begin dissolving the sugar. The wedges should look glossy and slightly relaxed while a thin amber syrup gathers at the bowl’s bottom. You’ll smell fresh peach and cinnamon before the fruit loses its shape. Skip the 10-minute rest and dry cornstarch pockets can survive into the filling. Resting starts controlled juice release so the thickener hydrates evenly. Preheat the oven to 200°F now so it's fully hot by the time the pan goes in.

Whisk the all-purpose flour, granulated sugar, remaining brown sugar, baking powder, remaining cinnamon and remaining salt for 20 seconds. Keep the milk at 68°F to 72°F and cool the melted butter below 100°F. Pour both into the dry mixture. Fold with eight slow J-shaped strokes and scrape the bottom once. Then rest the batter for 5 minutes. The batter should stay thick and lumpy with narrow ribbons falling from the spatula. Small flour streaks are fine, but dry pockets at the very bottom aren’t. Mix past 60 seconds and the topping can turn tight instead of tender. The short rest hydrates flour without building too much gluten.

Brush 1 tablespoon melted unsalted butter over the 6-quart oval insert while it stays near 70°F. Spread the glossy peach mixture into one uneven layer. Then spoon the rested batter over about 80 percent of the fruit in irregular 2-inch mounds. Finish this assembly within 5 minutes and leave narrow gaps where the syrup can rise. Slow Cooker Peach Cobbler with Fresh Summer Peaches should look patchy at this stage, not sealed under a smooth blanket. Peach edges should remain visible between pale batter islands and amber syrup. Covering every gap traps steam and makes the topping gummy. The open spaces let heat and fruit vapor move through the batter.

Set the slow cooker to HIGH and keep the lid closed for 2 hours 15 minutes. Then crack the lid open 1/4 inch and cook 30 to 45 minutes longer. Check the center with an instant-read thermometer. It should reach 200°F to 205°F while the peach syrup bubbles steadily around the edges. The topping should look matte and pale gold with darker cinnamon freckles and a few moist cracks. The fruit underneath should turn deep orange-gold and smell jammy. (I kept the lid sealed through my first batch, condensation left the center pasty. Venting fixed it.) Stop by 3 hours because extra heat turns the peaches mushy. Venting releases steam so the topping can set.

Switch off the slow cooker and uncover it for exactly 20 minutes. Wait until the filling cools near 150°F and the syrup thickens around the peach wedges. Cut down through the topping with a broad scoop and lift one eighth into a shallow white bowl. Add 1/4 cup vanilla bean ice cream and a light cinnamon dusting. The portion should hold rough layers while some amber syrup pools naturally around the base. The ice cream should soften at the edges but keep a cold white center for 3 to 5 minutes. Serve too early and the filling runs thin across the bowl. The rest lets cornstarch finish setting before the cobbler is portioned.