The Banana Chocolate Sando takes the plain banana-and-cream fruit sando and runs a chocolate element through it. A whole or halved banana lies along the length of two slices of soft white bread, but here the whipped cream is either folded with cocoa or chocolate, or a layer of chocolate cream or sauce is laid in alongside the plain cream so the cross-section shows a stripe of brown against the pale fruit. The point of difference from the simple banana sando is exactly that chocolate component; without it you have a different, plainer sandwich.
The craft sits in keeping a sweet, soft, three-part filling stable inside soft bread. The banana has to be ripe enough to be fragrant and sweet but firm enough to slice into a clean disc when the sando is cut, since a brown overripe banana smears and a green one tastes of nothing. The chocolate element is a balancing problem: too much and it flattens the banana into generic sweetness, too little and it reads as a smudge rather than a flavor. Good versions use a chocolate cream stiff enough to hold its own band rather than a thin sauce that bleeds into the white cream and turns the whole interior muddy. The bread is shokupan with the crusts trimmed, and the assembly is chilled so the cream sets and the sando can be cut into a clean rectangle or triangle that holds its picture. A careless one is a beige slump of melted cream and bruised banana with chocolate bleeding everywhere; a careful one is a tidy two-tone cross-section with the banana centered.
Variations layer in textures and richer chocolate. Some add a smear of chocolate-hazelnut spread for nuttiness, some scatter chopped nuts or crushed cookie for crunch, some use a dark chocolate cream to push the sweetness back toward bitter. A version with sliced strawberries joining the banana drifts toward a mixed fruit sando rather than a banana-chocolate one. The cream-only banana sando, lighter and milkier without any chocolate at all, is a separate sandwich and deserves its own article rather than being crowded in here.