itch.io

The source code is in the page if you want to check it out (cooker/Fruit.gd) but, basically, each fruit is a Polygon2D (it doesn't need to be one but it's easier this way) and the knife has a polygon too. Then you need to clip those two polygons to get the parts with Geometry.clip_polygons_2d(fruit_polygon, knife_polygon) that will give you 2 or more polygons. After that you need to set the correct UVs for those polygons with:

        var poly = splitted_fruit.get_poly()
        poly.polygon = points
        poly.texture = Poly.texture
        var half_size = poly.texture.get_size() / 2.0
        var uvs = []
        for j in points.size():
            var vec = (points[j] + half_size)
            uvs.push_back(vec)
            
        poly.uv = uvs

Which basically moves all the UVs to the correct position in the splitted polygon.
This way you have them splitted, you can add them to a RigidBody2D and apply some forces (like I did in the game) so they fly out of the screen.