In a skillet, heat butter and olive oil over medium heat. Once melted, add the anchovies and stir until they dissolve into the butter, this takes about 1–2 minutes.
Add the panko and garlic, stirring to coat everything evenly.
Toast for 5–7 minutes, stirring often, until breadcrumbs are deep golden and fragrant.
Stir in lemon zest and parsley if using. Cool completely, then store in an airtight jar for up to a week.