Preheat oven to 350°F (180°C).
In a 10-inch cast-iron skillet, soften 1⁄3 cup (76 grams) butter over medium warmth. Whisk in brown sugar, and cook dinner, stirring sometimes, till combination begins to caramelize, 4 to five minutes. Slowly whisk in lemon juice till mixed. Take away from warmth. Place banana halves, minimize aspect down, on high of caramel, slicing bananas to suit, if essential.
Within the bowl of a stand mixer fitted with the paddle attachment, beat granulated sugar and remaining 1⁄2 cup (113 grams) butter at medium pace till fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, separately, beating nicely after every addition. Beat in peanut butter and vanilla till mixed.
In a medium bowl, stir collectively flour, baking powder, baking soda, and salt. With mixer on low pace, steadily add flour combination to butter combination alternately with milk, starting and ending with flour combination, beating simply till mixed after every addition. Fastidiously spoon batter over bananas in skillet, smoothing high with an offset spatula.
Bake till a wood decide inserted in heart comes out clear and an instant- learn thermometer inserted in heart registers 205°F (96°C), 45 to 50 minutes. Let cool in skillet for 10 minutes. Fastidiously invert cake onto a rimmed serving plate. Serve heat or at room temperature. Refrigerate in an hermetic container for as much as 2 days.
