Whisk together yogurt, evaporated milk, and mustard in a bowl until well combined.

Set the yogurt mixture aside.

Heat 3 tsp. of garlic oil and paprika in a large skillet over high heat.

Add sliced portobello mushrooms and chopped red onions to the skillet.

Sauté the mushroom and onion mixture for approximately 12 minutes, or until softened and slightly browned.

Pour the prepared mustard mixture into the skillet with the mushrooms and onions.

Heat the mixture until it is warmed through, ensuring not to boil.

In a separate skillet, heat the remaining 2 tsp. of garlic oil over medium-high heat.

Add baby spinach leaves to the skillet in batches.

Cook the spinach for 2 to 4 minutes, or until it is wilted and a bright green color.

Season the wilted spinach with salt and pepper to taste, if desired.

Divide the wilted spinach evenly among serving plates.

Top the spinach with the portobello mushroom mixture.

Serve immediately.