Trim the crusts from the bread slices, then cut each slice into 4 small squares or rectangles.

In a small bowl, mix the softened butter with mayonnaise, garlic powder, and salt if using.

Spread a thin layer of the butter mixture on one side of each bread piece.

Place a small pinch of shredded cheddar cheese on the unbuttered side of half the bread pieces, then top with the remaining pieces to make mini sandwiches.

Heat a skillet or griddle over medium-low heat.

Cook the mini sandwiches for 2 to 3 minutes per side, pressing lightly with a spatula, until the bread is golden brown and the cheese is melted.

Remove from the pan, let cool for 1 minute, and garnish with chopped parsley if desired. Serve warm.