Preheat the oven to 300°F.
Line a sheet pan with parchment paper.
Add the oats, white sugar, brown sugar, sliced lemon, salt and poppy seeds to a food processor.
Pulse until the oats and lemon are evenly broken down and the mixture has a cohesive, textured consistency.
Add the olive oil and pulse until incorporated.
Spread the mixture evenly over the parchment-lined sheet pan, creating a thin, even layer.
Bake for 20 minutes, or until the bark is set and lightly golden.
Remove from the oven and allow the bark to cool for at least 1 hour.
Make the glaze just before using.
Combine the powdered sugar, lemon juice, lemon zest and poppy seeds in a bowl. Stir until completely smooth.
Pour the glaze over the cooled bark and spread it evenly from edge to edge.
Allow the glaze to sit for about 10 minutes, or until a light crust forms on the surface.
Break the bark into pieces and enjoy.