Preheat your oven to 350°F. Spread the oats evenly across a parchment-lined baking sheet and toast them until they are golden brown and aromatic. Depending on your oven, this can take 5 to 10 minutes. Stir occasionally to ensure even toasting and prevent burning, as burnt oats can impart a bitter taste to the final ice cream.

Using the same baking tray, toast the walnuts for 5 to 7 minutes, stirring them a few times to avoid scorching. Let the walnuts cool before roughly chopping and setting them aside for later.

Prepare the vanilla bean pod by removing the seeds. Reserve the seeds for a separate use, such as making vanilla sugar for future recipes. Save the pod for steeping with the milk and cream.

In a medium-sized pot, combine the homogenized milk, heavy cream, vanilla bean pod, and a pinch of kosher salt. Heat the mixture over medium-high heat until warm, then stir in the toasted oats. Allow the oats to steep in the warm milk mixture for 15 to 20 minutes, stirring occasionally. Taste the mixture to ensure the oats have infused their flavor into the cream.

Strain the mixture using a fine-mesh sieve lined with cheesecloth or a thin towel, squeezing the oats firmly to extract as much liquid as possible. Be cautious, as the oats may still be hot; allow them to cool slightly if necessary.

Measure the strained milk mixture to ensure you have 3 3/4 cups of liquid. If the oats have absorbed more than expected, top up the mixture with additional milk or cream. Return the liquid to the stovetop and gently reheat it.

In a separate bowl, whisk the egg yolks and granulated sugar until smooth and slightly pale. Slowly temper the egg mixture by gradually adding 1 cup of the hot milk, whisking constantly to prevent curdling. Repeat with another cup of the hot milk. Return the tempered mixture to the pot with the remaining milk and cook over medium heat, stirring constantly, until the custard thickens enough to coat the back of a spoon.

Strain the custard through a fine sieve into a container suitable for chilling. Cover with a lid or plastic wrap, pressing it directly onto the surface of the custard to prevent a skin from forming. Chill in the refrigerator for at least 3 hours or until completely cold.

Once the base is thoroughly chilled, pour it into your ice cream maker and churn until thick and creamy. As you transfer the ice cream into storage containers, fold in the toasted walnuts, ensuring they are evenly distributed. Cover the surface of the ice cream with a sheet of parchment paper, seal the container, and freeze for at least 4 hours before serving.