8 large egg yolks
1 cup packed light brown sugar, divided
1/2 cup Jif creamy peanut butter
1 teaspoon vanilla extract
6 ripe but firm bananas
2 tablespoons melted butter
6 tablespoons chopped honey-roasted peanuts
Whisk the egg yolks and 2/3 cup light brown sugar in a medium glass bowl until smooth. Set the bowl over a saucepan of simmering water, making sure the bottom of the bowl does not touch the water. Whisk until it has thickened and the sugar dissolves, about 5-6 minutes. Turn off heat. Whisk the peanut butter and vanilla into the egg mixture. Cover and leave the peanut butter mixture over the water to keep warm.
Peel bananas and cut in half lengthwise, then cut in half horizontally. Place 1/3 cup brown sugar into a pie plate. Spray a grill pan with nonstick cooking spray and heat over high heat until very hot. Brush bananas with melted butter, then carefully press each banana piece in the brown sugar until coated front and back, shaking off excess. Grill bananas until golden brown and caramelized, flipping once. Divide the bananas into 6 dessert bowls or glasses, then spoon the zabaglione over the top. Sprinkle each with the peanuts.