Peel potatoes and slice into 1/8-inch-thick rounds.

Heat 1 tablespoon of olive oil in a wide skillet over medium-high heat.

When hot, add a layer of potatoes to the pan and cook, turning once, 3 to 4 minutes per side, until golden and easily pierced with a knife.

Set aside on a plate lined with a paper towel.

Repeat with remaining potatoes.

When potatoes are done, add another tablespoon of olive oil to the pan.

Add garlic and cook until lightly golden and fragrant, about 1 minute.

Add spinach, with water still clinging to the leaves, and cook until bright green and tender, 2 to 3 minutes.

Transfer the spinach to a bowl and add goat cheese, ricotta, eggs, lemon zest and juice.

Stir to combine well. Season with salt and pepper.

Preheat the oven to 350°F.

To assemble the tart, lightly butter a 9-inch springform pan.

Line the pan with potatoes, covering the bottom and sides completely, overlapping slices for complete coverage.

Pour in spinach-goat cheese mixture.

Bake until firm and golden, 50 to 60 minutes.

Release the spring from the pan and gently lift off the sides. Set the tart on a plate, slice and serve immediately.