Heat oil in a medium nonstick skillet over medium. Add bananas and cook, undisturbed, until dark brown underneath, about 3 minutes. Turn and continue to cook, turning occasionally, until caramelized around the edges but still mostly firm, 2–3 minutes more. Add brown sugar and salt and toss just to coat bananas.
Transfer bananas (along with any liquid) to a small silpat-lined rimmed baking sheet (or a baking sheet coated lightly with nonstick spray). Freeze until hard, about 3 hours.
Let bananas soften just until you’re able to break them into large clumps (they should still be mostly frozen so this is really just a few minutes) and transfer to a food processor. Pulse until finely chopped, scraping down occasionally, then continue to pulse until a smooth paste forms, about 2 minutes. Add coconut cream and pulse until smooth and creamy, about 1 minute more. Add almond butter and pulse just until combined.
Transfer nice cream to an airtight container and freeze until firm, at least 3 hours.
Do Ahead: Nice cream can be made 2 weeks ahead. Keep frozen. If too hard, let soften for a few minutes before scooping.