Preheat oven to 350 F (180 C). Cut cod into 1" pieces, arrange in an 8x8" baking pan. Alternately, you can divide them between 4-6 individual ramekins. Set aside.
In a medium sauce pan over medium or medium-high heat, melt butter. Add onion and garlic and cook - stirring frequently - until onions are tender and translucent.
Add Dijon, whisking until well incorporated.
Carefully add wine to pot, whisking until smooth. Cook for 2 minutes, whisking frequently.
Add almond milk and heavy cream, once again whisking to combine.
Measure ¼ cup of the shredded cheddar and ⅓ cup of the Parmesan into a small bowl. Sprinkle xanthan gum over the cheese, gently tossing to distribute it over the cheese shreds. This will prevent clumping.
Add cheese mixture to the pan, stirring until thick, melted, and smooth.
Add summer savoury, season with salt and pepper, to taste.
Pour sauce over fish, stirring to coat and distribute evenly.
Scatter remaining cheddar cheese across the top of the fish mixture, then remaining Parmesan.
Spread pork rind crumbs on top
Bake – uncovered- for about 35 (individual ramekins) - 50 minutes (8x8 pan), or until fish is cooked through, and sauce is bubbly.
Serve hot.
Once cooled to room temperature, leftovers can be covered with plastic wrap - or transferred to an airtight container - and stored in the fridge.Reheat and eat within 3 days.
Notes
If using frozen fish, partially thaw it, cut it, then allow it to fully thaw and DRAIN before putting it in the baking pan.