Use softened butter spread thinly on the outside of both bread slices for even browning; room temperature butter applies more uniformly than cold butter and prevents soggy bread.

Place the gruyere or provolone directly on the hot pan first, then add the cheddar on top—this creates different melting points that enhance texture and prevents one cheese from overpowering the other.

Cut and add avocado only moments before grilling to prevent browning and oxidation, maintaining its bright green color and creamy texture throughout cooking.

Cook on medium-low rather than high heat to allow cheese time to melt completely while the sourdough develops a golden, crispy crust without burning on the outside before the inside cooks through.

Use a spatula to press down lightly and briefly (only once) halfway through cooking to improve cheese contact with bread, but avoid excessive pressing that squeezes out melted cheese and compresses the avocado.