Place 2 cups chopped strawberries in a small bowl; mash until broken up but some small chunks remain. Transfer the mashed strawberries to a fine-mesh strainer and allow any liquid to drain.
Place frozen banana slices, 2 tablespoons almond milk and ¼ cup cocoa powder in a food processor. Process until smooth and creamy, scraping down the sides as needed, 3 to 4 minutes. Transfer to a medium bowl; stir in the drained strawberries. Transfer the mixture to an airtight freezer-safe container; freeze until firm, at least 4 hours or up to 12 hours. Garnish with strawberries and sprinkle each serving with sea salt, if desired.