Wipe the oven cleaner off the countertop with wet paper towels right after it spills. Do not delay. Repeat two or three times.
Saturate the area with water and let it sit for 10 to 15 minutes. Then scrub the area clean with a rag or sponge.
Clean the area with hot soapy water to remove any remaining oven cleaner stains left behind. Repeat two or three times and rinse. If the stain does not come off with water or soapy water, proceed to the next step.
Clean the area with an all-purpose or multipurpose household cleaner -- per label instructions -- that lists rust as a type of stain it removes. Read your countertop's user manual first before using this type of product to check if it is safe to use. You may want to also test it in a discreet area of your countertop first.