Torched Banana Cake

Name: Torched Banana Cake
Ingredients: 4 Tbsp. unsalted butter, cut into pieces, plus more for pan; ¼ cup (packed; 50 g) light brown sugar; 1 tsp. Diamond Crystal or ¾ tsp. Morton kosher salt, divided; 3–4 ripe bananas, halved lengthwise; 1½ cups plus 1 Tbsp. (195 g) all-purpose flour; ⅓ cup (35 g) almond meal; 1½ tsp. baking powder; 1 large egg; 1 large egg yolk; 1 cup unsweetened coconut milk; ½ cup extra-virgin olive oil; 2 tsp. vanilla extract; 1¼ cups (250 g) granulated sugar, divided; Flaky sea salt; A 9-diameter springform pan; a kitchen torch