Raw kale salad may have its health benefits, but it's arguably not the most fun way to eat your vegetables. Smashing it into a sandwich with nutty Gouda and a quick homemade pesto is a serious improvement. If you're looking to fast-track this, because you absolutely cannot wait to eat, use store-bought pesto instead.
Toast the walnuts in a dry pan over medium heat, stirring frequently, until fragrant and slightly darker in color, 2 to 3 minutes. Transfer to a food processor, and pulse until coarsely ground. Add the basil and parsley and pulse just to combine. With the motor running, pour in ¼ cup olive oil until combined. Season with salt.
Heat 2 teaspoons oil in a saute pan over medium heat. Add the garlic and saute until fragrant, 1 minute, stirring, and then add the kale and saute until just wilted, 4 to 5 minutes. Remove from the heat.
Brush 1 side of each bread slice with olive oil, and gently sprinkle with salt. Spread the pesto onto the un-oiled side of 2 of the bread slices, and top each with the kale. Divide the Gouda on top of the kale.
Heat the remaining 2 teaspoons oil in a large saute pan, and transfer all 4 slices to the pan. Cook for 1 to 2 minutes to start toasting the bread and melting the cheese, and then cover with a lid until cheese is totally melted, about 1 minute longer. Top the kale slices with the toasted bread slices.