4 tablespoons (55g) butter, salted or unsalted
1/2 cup plus 2 tablespoons (110g) packed dark brown sugar
1 vanilla bean, split lengthwise and seeds scraped
1 tablespoon rum
4-5 medium bananas, (about 1 1/4 pounds, 565g, unpeeled)
For the cake
1 1/2 cups (175g) all purpose flour, or 1 cup (140g) all purpose flour plus 6 tablespoons (55g) teff flour
1 1/2 teaspoons baking powder, preferably aluminum free
3/4 teaspoon salt
1/2 teaspoon ground cinnamon
8 tablespoons (4 ounces, 115g) unsalted butter, cubed, at room temperature
3/4 cup (150g) granulated sugar
2 large eggs, at room temperature
1/2 cup (125ml) whole or lowfat milk, at room temperature
1 teaspoon vanilla extract
For the topping
1. To make the topping, heat the 4 tablespoons (55g) of butter, brown sugar, and seeds from the vanilla bean, in a 10-inch (25cm) cast iron skillet on the stovetop. (Add a sprinkle of salt if using unsalted butter.) Stir until the butter and sugar are liquified and start to bubble. Remove from heat and stir in the rum. Add the split vanilla bean to the skillet.
2. Peel the bananas and slice them in half lengthwise, into thirds, and arrange them over the brown sugar topping in the skillet. Preheat the oven to 350ºF (180ºC).
For the cake
3. To make the cake, whisk together the flour(s), baking powder, salt and cinnamon,in a small bowl and set aside.
4. In the bowl of a stand mixer fitted with the paddle attachment, or by hand in a medium bowl using a sturdy spatula, beat the butter with the granulated sugar until light and fluffy. Add the eggs one at a time, stopping the mixer between the additions and scraping down the sides.
5. On slow speed, mix in half of the dry ingredients, then the milk and vanilla, then the rest of the dry ingredients, mixing only until they’re just incorporated. Do not overmix. Scrape the batter over the bananas in the skillet and bake the cake for 30 to 35 minutes, until the cake feels done when you press it in the center. A toothpick inserted into the center should come out relatively clean.
6. Remove the cake from the oven and let stand for 10 minutes. Run a knife around the outside of the cake to help it release from the pan, and turn it out onto a serving platter or cooling rack, wearing oven mitts and taking care to avoid drips from hot caramel. Any caramel bits that may have stuck in the pan can be spooned back over the warm cake. Serving: This cake is best served the day it’s made, preferably while warm, but can be served at room temperature. I like it served on its own but it could be served with softly whipped cream or a scoop of vanilla ice cream or cinnamon ice cream.
Storage: The cake will keep for up to four days, if well-wrapped, at room temperature. I would not recommend freezing it as the texture of the fruit may change.