Now we have the great dessert dilemma.

At first boresome blush it might seem unappetizing, but the farm bill that Congress and Ronald Reagan are grappling over has a lot to do with America's ice cream and cake.

Wheat, corn, milk, sugar, peanuts--commodities caught in an intense legislative and budget disagreement--all figure in the recipe for a tastier tomorrow. That's how the ice cream and cake get mixed in.

House and Senate conferees are split over price support and target price levels for these basic farm products. The supports tend to determine market prices, which eventually affect the ice cream and cake. The targets--direct payments to farmers--have an effect on the budget, which the president is wary of increasing.

The conferees will reconvene next week, facing an impasse on the support levels that threatens passage of a final bill. The House is holding out for higher levels but the Senate, following Reagan's urgings, generally insists on lower levels.

The outcome could have implications for the economies of Latin American nations, the federal budget and the budgets of American consumers and farmers.

At its simplest, the argument is over how much federal help the farmer should get to help him continue to produce the abundant amounts of food ingredients that put meat, bread and dessert on the table. From the consumer's view, the support levels will have an effect on supermarket prices.

And now a look at the dessert table.

From the disputed wheat, comes flour for the cake. From the corn comes sweeteners for the cake and ice cream. Reagan says Congress is being too generous on price supports and target prices for them and wants them cut.

Then there's the milk, the main ingredient of the ice cream. Reagan says milk supports in the bill are too high, meaning that Uncle Sam will have to buy gobs of surplus milk in the future. Lower the support, slow down production and reduce government purchases, the reasoning goes. The other side says raise the supports, keep dairy farmers in business.

There's also disagreement on peanuts (we'll include those as ice cream topping), for which the legislation sets controversial controls to regulate supply and keep prices up.

And then you have sugar, which makes dessert what it is. The Senate approved a sugar support program, but the House rejected it. The conferees restored sugar to the farm bill, however, and the entire measure now is being threatened by a coalition of consumers and commercial sugar users.

Sugar appears to be shaping up as the stickiest issue.

Before the conferees last week slightly scaled down peanut and sugar support levels, a coalition of consumer and senior citizen organizations charged that the four-year bill will cost consumers an additional $10 billion for sugar, peanuts and milk.

Domestic cane and beet sugar lobbyists persuaded the conferees to come to their aid, arguing that low world prices threaten American producers' ability to compete and that they must have government price supports to make ends meet.

They were successful in part by fashioning a plan calling for repayment of support loans during the same fiscal year, thereby avoiding the budget "exposure" potential the administration has objected to on other commodity loans with longer repayment terms.

But critics such as Rep. Peter A. Peyser (D-N.Y.) argue that the new floors would force consumer prices up and that the government would end up with huge amounts of sugar offered by producers as collateral on loans that might be forfeited if world prices remained below the U.S. support level.

Another key feature of the program calls for fees and duties on imports, and the imposition of quotas if necessary, to prevent an accumulation of sugar by the government. Latin American sugar-exporting countries have protested bitterly that such steps would undermine their economies--an idea echoed by policy makers at the Department of State.

Administration officials are privately fearful that the sugar plan will have costly budget impacts. But their hands are tied in making that case by Reagan's earlier promise of support for a program in return for southern votes on his budget package.

By week's end the consumer coalition, joining forces with bakers, candy makers, soft drink, ice cream and food processing groups, notified the conferees they would work to defeat the conference report on the House floor unless support levels were not cut back even more.

Little is being spared in fighting the sugar battle. The commercial users' cause was being pushed by a newly hired advocate, attorney Kip O'Neill, son of House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.). "We've made no big deal of it," said Linwood Tipton, a director of the user group. "He's giving us advice on parliamentary stuff."

Peyser said he will make one final effort next week to persuade the conferees to reduce the 17.5 cents-per-pound support level they adopted. Failing that, he said, a floor assault will be mounted against the farm bill.

"So many factions of the agriculture community are unhappy that I feel confident about floor action," Peyser said the other day. "Dairy people are unhappy; some peanut people are unhappy; a lot of Republicans are unhappy with the sugar program."

The sweet-and-sour irony of this dessert dilemma: It's too rich for some, too sparse for others.